Friends All Along

A character is accosted by a stranger. Maybe he's a burly biker or a rude cop. They start arguing, and just when it seems the biker guy will break the other character's neck...

...they hug and start reminiscing about old times. They knew each other all along!

A good way to add some fake conflict on otherwise boring conversation scenes and to prepare hilarious pranks. A common way for a pair of Vitriolic Best Buds to be introduced.

Anime and Manga

 * It's much slower than it appeared, and these two actually have conflict, but from Hitohira are actually this.
 * In the Cowboy Bebop episode "Sympathy for the Devil", Jet yells "Hey fatty!" at a fat man in the bar. It seems like he is trying to distract him or start a fight, but it turns out they're old friends and "fatty" is an affectionate nickname.
 * Kinda what happens between Subaru and Ginga in Magical Girl Lyrical Nanoha StrikerS (episode 15): Nanoha orders Ginga to spar with Subaru, who immediately gets a strange expression on her face. The two begin the mock battle and at some point, it starts looking so real, the observers begin to wonder if there's The Glorious War of Sisterly Rivalry going on under their usual friendly facade... but then, they both smile and Caro comments that in reality, they love each other very much. Awwww...

Comic Books

 * Roxy and a rhyming biker called Poet in the Superboy comic.
 * La Muse in the eponymous comic, while in Harlem.
 * Such scene between Captains Haddock and Chester freaks out Tintin in The Shooting Star.
 * The first appearance of Buck's Uncle Frakkus, in Buck Godot: The Gallimaufry. Especially notable as he doesn't just verbally accost his nephew, they actually engage in (apparently) mortal combat! This is, apparently, a standard Hoffmanite greeting.
 * After this revelation, another character wonders aloud about Hoffmanite courtship, and is told that it starts with high explosives...
 * In Preacher (Comic Book), this happens between Cassidy and Si in the first book.
 * The staged fight between Mac and another gorilla in Grease Monkey.

Film

 * In The Empire Strikes Back, Lando does this with Han Solo when they get to Bespin.
 * Done in Strange Days, where a police officer grabs the hero (who is selling a contraband substance) and scares away his customer, and then they laugh about it and go have drinks.
 * Maverick:
 * Maverick and the Indian chief.
 * Maverick pulls a gun on a bank manager, causing an employee to think that the bank's being robbed. Maverick and the manager then reveal that they're really friends.
 * What about his being revealed!?
 * Mixed with Carnivore Confusion to odd effect in Kermit's Swamp Years; Horace D'Fly sings the opening theme before being swallowed by Kermit. Kermit then spits him out, and it turns out they're friends and they do this all the time.
 * In Ocean's Eleven (the remake), Danny Ocean turns out to be old friends with
 * Happens in Braveheart where the audience believes William Wallace and the big Scottish guy are old enemies when they're actually best friends.
 * A bigger version happens when the Scottish and the Irish army charge at each other. When it seems that they would gut each other, they stop right at each faces and start hugging and shake hands and later join forces together against the English army. Too bad they lost the battle.
 * In the opening sequence of Different for Girls, two schoolboys — one athletic, one sensitive — are stigmatized by their classmates because they seem to like each other a little bit too much. They go their separate ways. A few years later, the athlete (now a young man) meets an attractive young woman who turns out to be his sensitive schoolboy friend, after a sex-change. Romance ensues.
 * In the Fellowship of the Ring, Aragorn was hurrying to find a herb to heal Frodo that he didn't notice that someone had snuck behind him and held a blade to his throat. Said person happened to be his lover Arwen.

Literature

 * Ued in the Star Wars Expanded Universe novel Heir to the Empire with Chewbacca and an old pal.

Live Action TV
"Mac: I wiped the floor with the last person to break in here.
 * Between the initial pranks, the insults, the food-stealing and the general snarkiness, an unfamiliar viewer would think House was Wilson's office bully, not his "best-friend", thus using this trope on a weekly basis.
 * Urza greets his old friend Londo this way in the Babylon 5 episode "Knives".
 * Giles and
 * In the Supernatural episode Folsom Prison Blues, Sam and Dean get arrested so they can investigate a haunting at a local prison. While there, the brothers are harassed by the prison's Warden. Then, around three quarters through the episode, it's revealed the Warden is actually their friend Deacon, who asked them to investigate the prison in the first place, and helps them bust out.
 * Not to mention the pilot episode. We have a scene of two little boys escaping a burning house and their mother dying, cut to 22 years later. The younger of the boys (now an adult) and his girlfriend have some exposition conversation, go to a party, go home, and that night, he hears a noise downstairs. He goes down, gets into a fight with the intruder, who, after wrestling him for a few minutes, starts making snide remarks, revealing himself to be the older brother. Somewhat subverted in that Sam didn't know it was Dean at first.
 * In one of the earliest Gilmore Girls episodes, a man shows up in Stars Hollow on a motorcycle. When Lorelai and Rory ask if the man needs anything, he replies with something to the effect of "take off your top". After the Girls' initial shock wears off, the man removes his helmet revealing Chris, Rory's father and Lorelai's on-again/off-again Love Interest.
 * In Episode 6 of Leonardo, "The Lightning Box", Mac arrives at his home to find someone waiting for him.

Stranger: You've never cleaned a floor in your life.

(Beat)

Mac: Carlo Cazali! It's been years!"


 * In Torchwood, between Captain Jack and Captain John. They walk towards each other with severe expressions, like they're about to start fighting - then they start making out. Then, they do start fighting each other, so it may be a subversion... Then again, after that, they start catching up about life since the Time Agency...

Western Animation

 * Something like this happens in Teen Titans. When the Titans go to Starfire's birthplace, she immediately gets into a shouting match with a huge, haggard, tough-looking guard. With the rest of the Titans on their guard, the huge guard starts tickling Starfire, and the two embrace. Turns out he was her nanny.

Real Life

 * This flash mob in Oskemen, Kazakhstan.

Video Games

 * In Thane's loyalty mission in Mass Effect 2, the player encounters a character named Mouse, who, as the conversation plays out, was a street urchin who served as Thane's contact in the underworld.