Rampage From a Nail

A character is minding his own business when there is suddenly a commotion aroused nearby. A big mean wolf suddenly appears snarling and chasing everyone in town. No matter what happens, you can't seem to subdue the wolf. Suddenly, as the wolf turns around, you look and see that there is a thorn stuck in the wolf's left hind paw so you quickly trap the wolf. Once the wolf has been subdued, you pull the thorn out from the wolf's foot. The wolf gets back up again, but this time, he starts licking your face, happy that the thorn is removed.

This is when a creature of some sort wreaks havoc in a nearby community, due to the fact that there is a sharp object stuck on a part of its body. Once you remove the sharp object, the creature is no longer angry. Sometimes, the animal might just run back into the forest without a display of gratitude or affection for whoever stopped the pain.

Not to be confused with: For Want of a Nail

Compare: Androcles' Lion

Anime and Manga

 * This happened four times in Pokémon:
 * The Kanto episode "To Master The Onixpected" had Elite Four member Bruno capture an Onix after pulling out a Sandslash that had been lodged between two segments of its rock body.
 * The Sinnoh episode "Faced With Steelix Determination" involved a Steelix going on a mad rage near a village of Bidoof because of some shovels that Team Rocket had accidentally jabbed into its head. Made even worse when it was nearing a large lake during its anger (Steelix are Steel and Ground Pokemon and are weak against water). Fortunately, Ash and the gang, with help from the Bidoof, were able to remove the shovels before Steelix could fall into the lake.
 * Later Professor Oak proved his identity by identifying that a Tyranitar had a splinter in its foot. The Tyranitar didn't go on a rampage but its trainer said it had been acting grumpy lately.
 * A Unova episode that recently aired in Japan had a wild Gigalith that was terrorizing town while Ash was battling against the Pokemon Champion Alder. Alder then noticed that Gigalith had a nail stuck in its foot so he removed it.
 * The boar at the beginning of Princess Mononoke was crazy/evil because of a bullet.

Comic Books

 * This wasn't an actual nail, but there was a Superman/Hulk crossover story where Hulk is on a rampage and Superman discovers a tiny little machine is emitting a sound that is driving Hulk crazy. Superman destroys it and soon after Hulk begins to calm down.

Fairy Tales

 * The folk tale The Lion and the Mouse. Mostly likely the Ur Example of this trope.

Film

 * Kirikou and The Sorceress: The sorceress has a massive thorn in her back, stuck so deeply in the only way to remove it is with your teeth. When it's removed, she gets better.
 * Inversion: In House of Frankenstein, removing the stake from the heart area of Dracula's skeleton lets him instantly re-form and go on a "rampage" of bloodsucking.
 * The film Namu,The Killer Whale had one of these-Namu was provoked into a rage by someone throwing him a fish rigged with a hook. He finally calmed when someone found the hook and pulled it out.

Literature

 * Riftwar Cycle: A bear went on a rampage because it had an arrowhead stuck in it. The arrowhead was shown be made oddly or wrong, and its maker--also assumed to be the one who shot it, ended up wanted for murder--specifically of those the bear had killed in its rampage.
 * In The Silmarillion, Carcharoth ate the hand of Beren for a snack, which caused him to go on a mindless rampage, though he was already evil and violent to begin with. Possibly one of the most extreme examples of this trope--both in terms of deadliness of rampage and the pain.

Western Animation

 * The Care Bears Adventure in Wonderland had the Jabberwocky, who was in a state of crankiness, due to a thorn stuck in his paw. With the combined effort of everyone, the thorn was removed, inciting the Jabberwocky's Heel Face Turn.
 * An episode of Doug, with the eponymous character posing as his superhero persona Quailman, involved a giant monster created by Dr. Rubbersuit called Klotzilla that was rampaging throughout the city. Quailman then discovered that said monster had a thorn stuck in his foot and removes the thorn, helping Klotzilla from the pain he was in.
 * In the second episode of My Little Pony Friendship Is Magic Fluttershy manages to calm down an angry manticore attacking the group, and learns that its fury was because of a thorn in its paw.
 * In The Simpsons, a bear that assaulted Homer was aggressive because of some electronic chip attached to his ear.
 * In an episode of Ed, Edd 'n' Eddy Ed goes on a rampage that genuinely scares the entire cast because.
 * SpongeBob SquarePants: "The Smoking Peanut" has a giant clam behaving this way. Everyone thinks it's because it had a peanut thrown at it, but later it turns out its egg was stolen.
 * There was also one episode in which Gary is entirely unruly and goes around biting people. It turns out it's from a splinter. A very, very large splinter. Large enough to almost make this example a parody.
 * Dink the Little Dinosaur: Dink and his friends had to convince a really huge dinosaur to help them in one episode. He initially refused, stating he had his own share of trouble. Considering the trope page where this is being told, it's not hard to imagine what it was about.

Real Life

 * It was suspected that the rogue elephant of Aberdare Forest behaved the way it did because it had a bullet lodged near the nerve center of its tusk.