Mundane Solution

A very exotic device or problem, against which all manner of intricate, powerful devices or strategies fail, is counteracted by something incredibly simple and mundane. It can't be solved by their conventional solutions of More Dakka, Attack! Attack! Attack!, diplomacy, or other Rule of Cool applications. Applied Phlebotinum, it seems, often turns out to have a weakness to some household product.

Supernatural beings in both Eastern and Western mythology have a tendency for strange weaknesses, like a demon's obsessive-compulsive need to count dropped grains of rice or a vampire's vulnerability to garlic and sunlight.

May overlap with Not So Invincible After All. Contrast with Mundane Utility, where something exotic is used to solve something mundane, and Weaksauce Weakness, where a no less powerful individual gets strange weaknesses or power. A favored tool of the Combat Pragmatist. Cut the Juice is one particular example of this, as is Cutting the Knot (the weakness of string is a sharp blade!). Percussive Maintenance is a subtrope. See also Depleted Phlebotinum Shells, when the weakness is weaponized. Related to Muggles Do It Better.

Anime and Manga

 * If you've watched the second season of The Slayers and read even a little of the supplementary material, you're aware that . It goes without saying that while Lina Inverse might be able to pull out the big guns and defeat him, nobody else stands a snowball's chance in Hell of bringing that guy to his knees. So when Lina's otherwise occupied and her teammates have no choice but to take the guy on by themselves, they pull out their own "big guns" and defeat him with   sure wasn't expecting that.
 * A powerful, dangerous Mazoku has Lina trapped in a closed space region from which a human would otherwise find impossible to escape. Lina prepares a magic spell and ... summons an absolutely normal bird. The summoned creature itself is useless in a fight but Lina is actually abusing summoning rules. That absolute normal bird broke through dimensions to get to her, giving her a way out of the closed space region.
 * In one of the episodes of the anime Birdy the Mighty, the space-babe informs the hero that the slime based shapeshifting horror can only be hurt by a chemical weapon, specifically a surfactant. The hero promptly runs home and grabs a bottle of dishsoap.
 * The Mahou Sensei Negima manga has a flashback showing the epic battle between Nagi (The Thousand Master) and Evangeline (an incredibly Little Miss Badass and vampire), who are two of the most powerful mages alive. After some suitably epic banter between the opponents, Nagi ends the battle before it even begins by catching Eva in a pit trap filled with onions and garlic. Game over.
 * Super geniuses Chao and Hakase spent two years perfecting an AI to run her Cassiopeia because it's so complicated. Negi spent five seconds summoning two very low level magic spirits (minor prediction and minor dexterity or something) to time predictions then operate the dial for him.
 * Not to mention Chao's "secret weapon," which she didn't use in first place because she was afraid of the damage it could cause--a copy of her family tree.
 * A powerful fire mage in To Aru Majutsu no Index is stopped by... a sprinkler system. At first, he scoffs at the lead for thinking that his fire summon could be put out with just a little water, and he's right about that--the real point was for the water to blur out the printed runes that were continuously allowing his fire to regenerate after being destroyed. With that ability disabled, the rest is easy.
 * Pretty much every fight in the series ends up like this considering the bad guy has some power on the lines of warping reality by willpower alone, the ability to change vectors (as in, the guy is immune to any attack and can turn any force in any direction he contacts, including light or cause massive explosions and stuff) passively, actual angels or create giant rock monsters, and the hero... can cancel magic and stuff with his right hand, and that's it. So he punches them in the face. Hard enough to dent concrete, yes, but still.
 * In Ash's first battle against Brock in Pokémon, Pikachu goes up against a Onix, which is immune to electrical attacks. He wins (sorta) by shooting lightning everywhere and accidentally starting a fire that sets off the sprinklers and douses Onix For Massive Damage.
 * This is a common plot device in Haruhi Suzumiya, where Kyon repeatedly saves the world by doing very mundane things, like, , or.

Comic Books

 * Similar to the Smallville example below, Superman shuts down Livewire by simply getting her wet enough so she ends up short-circuiting herself. Then there's the rubber suit he put on to prevent her from zapping him and Parasite from leeching his powers for a two-for-one deal.
 * In The Sandman: Endless Nights, the people in a castle bar Death from entering their home with a magic gate, rendering themselves immortal as long as they stay inside. After trying for about two hundred years to get in, Death (who is an attractive Perky Goth) asks an off-duty soldier for help. Not knowing who she is, but smitten and eager to impress the pretty girl asking him for help, he tears down the gate with brute force.
 * The Transformers Generation 1 comic had Scraplets - a sort of contagious "flesh-eating disease" which affects transformers. It was inevitably fatal, as well as completely uncurable, apart from some apocryphal records of a substance so rare that its very existance was doubted. Standard procedure for dealing with it was total quarantine followed by destroying the infected individuals. Oh, that nigh-mythical, incredibly rare cure?
 * An Uncle Scrooge comic where villainess Magica DeSpell sprays Scrooge with a potion that causes his face to change to the face of whoever he looks at. Eventually Scrooge and company find that the solution is to simply wash the potion off with soap and water.

Film

 * In Evolution the aliens are killed by Selenium. Found in shampoo.
 * In the movie Star Trek: First Contact, Captain Picard uses a (Hard Light) Thompson submachine gun to kill the Borg who are immune to the advanced phaser weapons the Federation normally uses.
 * In Spy Kids 2, the kids are presented with several cool gadgets, including the "coolest" one, which is described as a "Machete elastic wonder" (it's an ordinary rubber band). At the end of the movie, the kids use the rubber band to disable the bad guy's doomsday device.
 * In the first Saw film, two detectives manage to catch Jigsaw in his hideout. Jigsaw activates one of his traps to distract them so he can escape. The trap involves two drills closing in on some poor bastard's head, and the key needed to free him was on a janitor-sized key ring with dozens of others. After a few seconds of trial and error with the keys, one of the detectives gives up and shoots both of the drills to deactivate them.
 * In the Thomas the Tank Engine movie, Mr. Conductor scares off the evil Diesel by threatening him with... sugar. Done better in one of the unadapted Reverend's stories, where the insolent diesel Spamcan is threatened with a can opener.
 * Truth in Television, however. Pouring sugar into a diesels gas tank will cause it to mix with the gas inside, eventually causing the diesel to explode.
 * In Executive Decision, a bomb is "defused" by the simple expedient of thrusting a plastic swizzle-stick between two electrical contacts, thus preventing the detonator from firing.
 * Also in Raiders of the Lost Ark, where upon meeting the expert swordsman about to cut him to ribbons, even with other ways to fight back, Indiana Jones simply draws a gun and shoots him. Harrison Ford was ill due to the previous night's dinner disagreeing with him, so the planned action scene was abbreviated into a quick joke.
 * Beware! Children at Play ends will all the adults just ganging up on the feral children and massacring them, primarily via shooting.
 * In Casper, the bully ghosts are sucked up by a vacuum cleaner.
 * In Casino Royale, Bond chases a crook who uses acrobatic Le Parkour to navigate obstacles quickly. Bond doesn't have these kinds of skills, so he uses ingeniously mundane solutions, such as simply smashing through a wall instead of bounding over it.
 * Johnny English Reborn parodies the classic spy film on foot chase scene with this. While the Vortex agent uses quick parkour movements and dramatic acrobatics to escape, English non-chalantly uses the stairs, elevator, shimmies through a gap on a roof and opens a fence door that the agent leaped over to keep up, and catches him in the end.

Literature

 * In the story Count Beet, the Count, an earth spirit, can turn beets into whatever items he wishes, or even people, for as long as the life in the beet lasts. The princess he captured and wishes to marry eventually hits on the perfect plan of escape: She tells him she wants a huge wedding with all manner of attendees and decorations, and to that end must know exactly how many beets the Count has in his garden. While he's busy counting... and re-counting... and re-counting... she simply walks out.
 * Very common in the Discworld novels, especially where the witches are concerned. The primary example would be Magrat's magic wand in Witches Abroad: Magrat has a great many ceremonial athames, covered in filigre and runes and whatnot. Eventually she learns that the most magical knife is the reeeeelly old breadknife that not only can perform all the magical rituals the athame can, but also cut bread.
 * In the early Rincewind book Sourcery, Tyke Bomb Coin, the eighth son of a wizard and thus a Sourcerer (a wizard squared, and the reason wizards aren't allowed to get any) not only wields unstoppable magical power greater than anyone else alive but causes a huge rush of magical power to every other wizard on the Disc. Result: impending replay of the hugely destructive Mage Wars. How does Rincewind, self-professed Dirty Coward and the worst wizard in the world, if not ever, handle this?
 * It's mentioned repeatedly throughout the books that being being a wizard or being a witch is all about not using magic even though you could and instead relying on mundane solutions, because the magical solution will eventually come with a price tag, and it'll be a bill you can't afford to pay.
 * Granny doesn't always get it right; in Wyrd Sisters, she uses her most powerful Headology on the Duchess to make her see herself the way she really is, and is shocked when it has no effect. At which point Nanny Ogg hits the Duchess over the head with a cauldron. And in Lords and Ladies, she spends some time Borrowing to find out what's been happening while they were away, and learns that a group of girls are going up to the Dancers. Nanny, meanwhile, has learnt exactly who they are by just asking her son what's going on.
 * In a case similar to the Wicked Witch of the West, in Patricia C. Wrede's Enchanted Forest Chronicles, wizards can be dissolved by soapy lemon water. It is found out that lemon juice is a necessary ingredient. (The wizards do come back eventually, though.)
 * In Raymond E. Feist's The King's Buccaneer, Nakor and Anthony confront the Lady Clovis, a very powerful sorceress. Nakor tricks her into erecting very powerful anti-magic defenses, at which point he defeats her by throwing pepper at her then hitting her with a bag of apples.
 * Four words from science fiction author Larry Niven: "A knife always works".
 * Harry Dresden frequently runs into foes who are resistant to his magic. One confrontation with a spell-proof ogre is resolved when Murphy cripples the orge with a chainsaw and Harry drenches the ogre in gasoline and ignites it. Harry is also one of the few White Council wizards willing to use firearms and frequently uses his staff or blasting rod as a cudgel.
 * In Turn Coat, Morgan talks about how he once had to take on a skinwalker, an incredibly powerful demigod horror with a hefty resistance to magic. He knew he'd get pounded in a straight fight, so instead he lured it into following him to the middle of nowhere in Nevada. Specifically, a nuclear testing ground. He stepped into a portal to the Nevernever just as the bomb went off. Morgan 1, Eldritch Abomination From the Dawn of Time Did You Just Punch Out Cthulhu?.
 * In fact, mundane weaponry is the accepted way for wizards to kill if it ever must come to that, as killing humans with magic carries not just the obvious moral and legal ramifications but also corrupts the soul. The Council's enforcers carry big ol' swords for this reason.
 * Most of the crafters in the Codex Alera have weaknesses like this. Firecrafters have Elemental Baggage at their command, and they're useless when it's raining they're soaked; Windcrafters can be neutralized by burying them in dirt, watercrafters are useless if dehydrated and surrounded by fire, and earthcrafters can't do anything unless they're touching the ground. In addition, wind furies are damaged by salt, which is a problem if someone throws some at you when you're a mile up in the air. All of these get exploited at some point or another, whether in fights or to keep the crafters in question prisoner.
 * In John Varley's Demon, the war against Gaia gets a boost when they discover that zombies are destroyed by a witch's recipe for . It's hinted that Gaia, who by this time is batshit crazy and running the war as a game, built in this highly unlikely weakness as one of her private jokes and then forgot about it.
 * A Dragaeran saying: "No matter how subtle the wizard, a knife between the shoulderblades will seriously cramp his style."
 * In The Lord of the Rings, Gandalf tries to open the gate to Moria for many hours with spells, etc., until he realizes to actually do exactly what the inscription on the gate reads, which is to say the elvish word for "friend". Once Gandalf utters the words, the gate starts to open. (In the film version, it's Frodo who comes up with the solution.)

Live Action TV

 * Stargate SG-1: The team's minds were swapped around by a device that can exchange minds, but not exchange them back between the same two people. They overcame this by playing "musical chairs" with each other's bodies until everyone was back in the right place.
 * Another episode has Carter, an Ascended Daniel, and Jonas Quinn trying to figure out how to open a secret chamber to find an artifact. Daniel and Jonas look around for clues until Carter, noting how they don't have much time, tells them to get out of the way and blasts the compartment open with her P90.
 * There's at least one other episode where, to disable some kind of Goa'uld technology, Teal'c or Carter says they need to remove specific crystals from the control panel... and then Jack blasts the lot of them with his P90, which does the trick anyway.
 * Daniel does this in a later season to eliminate the Black Knight trying to kill Colonel Mitchell. He tries to figure out the complex sequence of panels to push to disarm the device, then finally gives up and just shoots the crystal tray.
 * Again in Stargate Atlantis. A piece of Lantean tech has swapped Dr. Keller's mind with a thief. Ronon solves the problem by shooting it.
 * Another example has Bra'tac guiding SG-1 to disable a Goa'uld mothership. Bra'tac explains how they'll need to climb down to the shield generator, fight off the guards, before finding a way to manually disable the generator. O'Neill just tosses a handful of grenades down the Shield Generator shaft and walks away as it explodes.
 * An early example is when the good guys realize that the Goa'uld's personal shields are really good at fending off energy beams and conventional guns, but slow moving objects like a thrown knife or arrow go right through them.
 * The Replicators were unstoppable, vastly advanced machines who decimated the Asgard's home galaxy; turned out you could just shoot them. The reason the Asgard had so much trouble with it is that they had invented energy weapons so long ago that they simply never considered shooting them. (In their later appearances, it becomes clear that while simple kinetic weaponry works fine on Replicators when they're only the size of a cat, they work fast and grow rapidly. If you don't nip a Replicator infestation in the bud, soon you'll be facing car-sized ones that you can't stop without an anti-tank weapon, and then ship-sized ones that nothing can kill.)
 * Some shows that feature high technology or magic also feature a moment or three where the most high-tech or ultra-powered shield is useless against an ordinary handgun. Or, if that still fails, a slingshot. Sometimes there's a huge buildup of suspense beforehand, and the guy about to use the gun goes through (or is expected to go through) an intricate ritual necessary to summon up the otherworldly powers to BANG!
 * To cite some examples: Wizards and Stargate SG-1.
 * Doctor Who:
 * In "The Pirate Planet", a machine is destroyed by hitting it with a spanner, albeit telekinetically.
 * Mickey tended to have simple solutions to problems. To get past a locked door, with coaxing from K-9 he just rammed it with a car; then to shut down the alien-influenced supercomputer, he pulled the power plug.
 * In Smallville, a depowered Clark faces a foe who has Psycho Electro powers, but they've gotta be fed almost constantly (if he's zapping you with one hand, he's drawing power from a source with the other.) Clark stops him by shutting off the power. (A great contrast to other episodes involving depowerment. Usually, he gets his powers back in time for round two.)
 * Subverted in a later episode. Clark tries to stop the rampaging Metallo by triggering an EMP wave. It shuts him down, but he restarts in a few seconds. Clark then takes him out with his heat vision and super speed.
 * NCIS had an episode where Gibbs has to shutdown a computer server before it can upload secret data to the Internet. McGee tries to talk him through the complicated process of hacking the security. Gibbs simply unplugs all the power cables and when this does not work due to battery backups, he simply shoots every piece of electronic equipment he sees in the room.
 * The very first episode of Chuck has the titular character disarming a complex laptop bomb with... wait for it... a virus-ridden porn site.
 * A sketch on Saturday Night Live had a group of defeated former James Bond villains (mostly from the Roger Moore films) discussing how to deal with James. One points out that if you're close enough to try something like dropping a poisonous spider down his back, "Just shoot him!"
 * In Supernatural,  can be temporarily beaten by cleaning solvents containing borax. And decapitation after, but the Borax comes first.
 * In season 6, The Fair Folk can be stalled by spilling grains of salt or sugar, that they compulsively have to count, as in the trope description.

Tabletop Games

 * In Mage: The Ascension, magic is indeed impressive given enough prep time, but mages taken by surprise tend to be in big trouble, being simple humans with none of the unique physical powers most other supernatural creatures have (vampires, werewolves, demons). That's why having a gun, sword or baseball bat with you always pays off.
 * In D20 Modern, there are classes of monsters that are tougher than the standard monster manual fare; to balance the fact that they are functionally invulnerable, they also have a table of unusual Weaksauce Weaknesses, ranging from 'the laughter of children' to 'Elvis memorabilia'.

Mythology

 * Older Than Feudalism: In Greek Mythology, King Gordias tied a cart to the gate of Persepolis with a knot that nobody could untie; prophecy said that whoever did untie this would become ruler of Persia. Alexander the Great is said to have solved the puzzle by cutting through the knot with his sword. (Another account features Alexander merely removing the pin that held the knot and then untangling a little rope. A more thorough, yet no less mundane, solution suggests he fished out one or both ends of the rope and undid the knot correctly.)
 * According to Japanese urban legend, if Kuchisake-onna approaches and asks if you think she's pretty, answering no will get you slashed to pieces in a violent rage. Answering yes will get you slashed to pieces because the word she uses for "pretty" (kirei) is a near-homophone of a word meaning "to cut" (kire). Giving a neutral answer like "you're so-so" will confuse her into letting you go.
 * Kuchisake-onna can also be bribed with candy. Or, in most recent versions of the story, you can excuse yourself and claim you're too busy to chat with her.

Video Games

 * The Big Bad of the Gamecube Custom Robo, Rahu,  At one point it comes across a Robo, which in those days was nothing more than a children's toy.
 * In the original Paper Mario there was a chest in Shy Guy's Toy Box containing a badge that was guarded by Anti Guy, who would let you have the treasure if you gave him a Lemon Candy. This is generally easier than fighting him since he's ridiculously strong.
 * In the Dark Sun games by SSI, mages, clerics and psionics are incredibly powerful. While a few high-level spells exist specifically to shut down a spell-caster, with a relatively large chance of working, the easiest solution is to just hit them: the turn after being hit, they are completely unable to use anything magic or psionic (of course, this is also true for your characters).
 * This occurs at the end of the final boss battle in Portal 2. It turns out that the new physics warping gels all wash off in minimal amounts of water. You knew that, because it was required to know for previous puzzles. The boss wasn't around for that part, and thus.
 * In Psychonauts, mental inefficiency is actually cleaned up with a cobweb duster. It helps that they're literally "mental cobwebs".

Webcomics
"Little girl: "Yay! Hey Mamma! I'm inna show!""
 * Girl Genius had Gil attempting to catch Zeetha with a cage clank. Said clank missed, and went on a rampage trying to catch something. After everybody else failed to defeat it using various means, Krosp checks with Gil to be sure that the clank will not hurt whatever it catches, then tosses a little girl into the robot and lets it capture her. Having achieved its objective, the bot promptly settles down and simply sits there, with the little girl happily inside.

"Moloch: This winch looks pretty sturdy, and there's some rope over there... *turns around and notices he's become the subject of several disapproving glares* ... and then at the bottom it could turn into a giant caterpillar or something?
 * Also, when everyone is trying to kill/cure Agatha, Gil, and Tarvek, one of the machines goes haywire, and the Sparks start screaming about how everything is going to blow up, and "NO FORCE ON EARTH CAN STOP IT!" Then, the machine spontaneously stops. Cue everyone looking at Von Zinzer, holding the power plug.
 * Moloch Von Zinzer is very good at this sort of thing. It tends to annoy Sparks, who don't like having their drama harshed by a Mundane Solution.

Sparks: No, you've already ruined the fun."

"Nerd boys: Ow! The plastic, it hurts!"
 * In The Inexplicable Adventures of Bob, after the Space Pirates of Ipecac have gone to a great deal of trouble to steal some Unobtainium called borfomite on a distant planet, they realize they have to combine it with plain Earth caramel to make it power their BFG. This is far from the only example, as part of Bob's shtick is his knack for hitting upon simple solutions to bizarre problems.
 * The Order of the Stick took a page out of the Engineer's book and used a gun (or bow, rather) to solve the Knights and Knaves problem in this strip.
 * When the clue hammers in El Goonish Shive were shut down, Susan was suddenly deprived of her habitual method of dealing with inappropriate comments. Enter Catalina Bobcat with a toy hammer...


 * Xkcd tells us how to beat cryptography in the kneecap.
 * Also known as rubber-hose cryptanalysis. For obvious reasons, this method is unfit for gathering court-admissible evidence.
 * Bigger Than Cheeses mocked the difference between the way Hollywood stops hackers, and the way you should stop them.
 * In The Adventures of Dr. McNinja, Gordito dealt with Victor, an obvious villain claiming to be a plumber, by hiring another plumber and firing Victor.

Web Originals
"Katie: But he has unlimited dark magical powers!
 * In Journey Quest Perf demonstrates a terribly simple solution to an enemy mage.
 * In Cracked's After Hours, they point out that that muggles had just known about Voldemort, we would have solved the problem by simply blowing him up.

Michael: Yeah, that he has to aim through a wand! We can fire a thousand missiles. From space. With iPhones."

Western Animation

 * In The Venture Bros, one of Doctor Venture's actual good inventions over the run of the show was an impenetrable force field. Unfortunately, he gets stuck on the inside with the president, a broken control switch and no way to get what was needed to fix it. Throughout the episode, the White House maid touted the cleaning power of club soda. It turns out to be the only thing that can break up the force field.
 * Child, a little club soda can get out anything.
 * In an early episode of Xiaolin Showdown, the Monks are tackling an obstacle course, where they jump through hoops and swinging logs and such to retrieve a stuffed dog at the end of the circular track, back near the starting line. When it comes around to Clay's turn... he turns around and grabs the dog from the end of the track. As Clay says "I don't see the point of all that hoppin' around, so long as I got the dog." At the end of the same episode, he wins a "sparrow catching" Showdown by filling his hat with seeds to lure the bird. Simple solutions to complicated problems!
 * Fitting with the Aesop of that episode, an evil mime has trapped the monks in an invisible prison. They spend most of the episode trying to blast their way out of prison.. then they get out by miming a door and opening it.
 * In the very first episode, several of Jack Spicer's robot minions are defeated by turning them off. Jack wonders aloud why he made the On/Off switch so obvious.
 * Yet another episode has a When You Snatch the Pebble-style test, which Omi passes by asking nicely for the objective. Xiaolin Showdown is quite fond of this trope in general.
 * In Futurama, (at least, in the comic continuity) pepper is actually stockpiled by the government, because a race of giant-nosed aliens who once conquered Earth had a fatal weakness to it. It's fun to imagine that government armories in Futurama are filled with mundane things such as hot sauce and Windex, all the specific weakness of one hostile alien species.
 * In the episode "Fear of a Bot Planet", a robot-made B-movie about those terrifying humans and the threat they pose ends with one of these. "The human was impervious to our most powerful magnetic fields, yet in the end he succumbed to a harmless sharpened stick."
 * The Teen Titans faced not one, but TWO villains who were defeated once they turned on the sprinkler system in the store the villain was robbing.
 * in Static Shock, Static has been known to deal with electricity-immune enemies by using his powers to magnetically manipulate nearby metal objects instead. It's functionally telekinesis.