Butters tries to do this with his Professor Chaos alter-ego, but it doesn't work too well as most of his schemes are just too inefficient, ineffective, and downright stupid, and once causes him to lose his eye in an accident while he was having a mock battle with the main characters and they forgot they were using real weapons.
But by himself, he does get Cartman back, in a big way.
Kyle: Butters, do you really think it's fair to lie like this?! Let me tell you, if you don't haveó!
Butters:[snaps] No! Let me tell you something, fellas!! You always take advantage of me. And after reading Catcher in the Rye, I've learned you're nothing but phonies! I'm not letting you trick me this time. So the four of you can just suck on my wiener.
[storms off, leaving the other boys speechless]
Cartman:[beat] That inconsiderate jerk...
And by the time of the episode The Coon, the town seems to regard him as superhuman.
Cartman himself in "Scott Tenorman Must Die."
Cartman tries it again in the Coon vs Mysterion trilogy, after several rather unheroic actions lead to him being evicted from the Coon and Friends club (who also keep the self aggrandizing name "because it pisses him off") he actually teams up with Cthulhu and banishes them to an alternate dimension, along with brutally killing millions of other people he finds to be "evil".
Scott Tenorman pulls this on Cartman on 201 when he reveals that they both shared the same father, whom Cartman killed and pureed into chili in the previous episode with Tenorman.
One of the villains in Batman Beyond was a high school peer of Terry named Willie, who decided to take revenge on his tormentors at school by controlling a Humongous Mecha used in construction.
And in another episode, it turns out that not only Willie spent time in the prison yard working out, the massive jolt that stopped his Golem control gave him strong psionic powers.
* Terry shocks the Joker with a joy buzzer—which disintegrates the chip containing the Joker's mind, effectively killing him *
Stan, Xander Crew's assistant on Frisky Dingo, did this after calmly explaining to his employer that after Crews went missing, Stan had him declared dead and took over his multi-billion dollar corporation. After hanging up, he said "Who's laughing now, Crews? Ha ha... Me. I am laughing."
Earlier, one of the X-Tacles punches an incapacitated Crews in the face and says "Who's laughing now, Crews?" Xander Crews responds "I wasn't laughing before!"
Baby Doll: You all remembers what happened the last time I had a birthday. Poopy old Spunky pushed my head in the cake. Everybody laughed and laughed. [smashes cake in his face] Well, I'm laughing now!
This was an unusual example in it that actually illustrated just how delusional Baby Doll was. Not only was Cousin Spunky just a character on the TV show she starred in, but it wasn't even personal. The actor was just following the script that was written for that particular scene. He even points that out.
And she admits it, not that it makes a difference:
Baby Doll: [in adult voice] It was real to me!
In "Joker's Millions", a rival gangster, Edward 'King' Barlow, died and left Joker 250 millions in cash, jewels and gold. Joker blows through it to buy himself liberty, a luxury home, and a new Harley. Then, as he's collecting money to pay inheritance taxes, Joker finds out he's been had.
Darkwing Duck subverted this one. In one episode, Darkwing is stranded on a planet where EVERYONE is a superhero...except for one man known as Ordinary Guy, who all the other inhabitants live to rescue from peril. Unfortunately for him, the "heroes" tend to PUT HIM in danger just so they can save him from it. Finally, he snaps, and becomes the planet's very first villain, with the dastardly moniker of "Not-So-Ordinary Guy." The heroes, having never actually fought a bad guy before, are clueless as to what to do about this.
Tucker in Danny Phantom. Usually the ignored Butt Monkey, Tucker becomes aware of it when he tries to run for school president in one episode. It chain reacts to him taking over the entire school via a magical scepter until Danny sets him straight. Unfortunately he still gets the ignored status for the reminder of the series.
An episode of Fillmore! dealt with a group of kids who teamed up to get back at their bullies in the most spirit-breaking fashion. An Aesop of this was that there are better ways to deal with bullies.
El Tigre does this with Sergio. After being made the laughingstock of Miracle City, he declares revenge on Manny/El Tigre with his evil robot persona, Senor Sinestrio.
Martin Mystery finishes off its 3 season run with the two part episode It's Alive!, where all the frustration of Diana's being lesser than Martin in the Center, and his constantly annoying her to no end, is finally ignited when she's given a 'Needs Improvement' evaluation over Martin's 'Glowing Evaluation'. A bit more of Martin's prodding as a result of that sends her over, and when given the chance to join Octavia Paine's organization, she leaps at the chance. She then proceeds to humiliate Martin by stealing two monsters away from him, as a result of his over-confidence streak, and laughs after the second capture. The seconds involves Octavia revealing her true intentions for the monsters, leaving her and Martin to stop her Super-creature from destroying the Center.
Bullies used to pick on me because I sang in choir But something very strange occurred when I kept singing higher The ruffians around me quickly fell into a trance And it was then, with wicked glee, I made those puppets dance!'' I'm the Music Meister!
Another one comes from some of their Star Wars sketches. At one point, when Anakin is coming back from the Sand People with his dead mother in his arms, Owen Lars cracks a joke about how "That makes him Little OrphanAni!" Anakin protests that it's Too Soon, while everyone else tells him to get over it. Later, when the stormtroopers are interrogating Owen and Beru over the location of C-3P0 and R2-D2, and the stormtrooper squad is about to set Owen and Beru on fire, the leader of the squad leans over to Owen and says "Oh, and I have a personal message from Lord Vader; he says now you can laugh at that Little Orphan Ani joke". Owen looks shocked and stunned for a second, then chooses to give Vader the finger as he dies by responding "You tell him it was funny then, and it's funny now! Little Orphan Ani! Tell him that to his face!" RelevantLinks
Quoted verbatim in an episode of TaleSpin by a now-gloating Butt Monkey after his rather amoral plan to be taken seriously appears to be succeeding.
Barnacleboy in SpongeBob SquarePants becomes a villain after various put downs by the people he saves. To be fair though, Spongebob promises to respect him even though it doesn't convince him.
Family Guy: In Dial Meg For Murder, Meg goes to jail for housing an escaped convict. When she comes out, she's tough, and gets payback on the people who mocked and abused her the past few seasons.
In Ed, Edd 'n' Eddy, Jimmy is the Butt Monkey that even nature picks on (a Squirrel once somehow dropped a tree on top of him, apparently on purpose). However, when the Edds note well, Eddy did, but this show is no stranger to Misplaced Retribution go too far and Break the Cutie, he reveals himself to be an extremely able Chessmaster and arranges a complicated plan resulting in all the kids chasing them down and pelting them with fruit, then getting dragged away by the Kanker Sisters. Beware the Nice Ones indeed. Also has traits of Hoist by His Own Petard, since it was Eddy that taught him to be a scam artist to begin with.
Eddy says this word-for-word at the end of "Hands Across Ed" when he has a magnet to ruin Kevin and Rolf's show. Unfortunately, it backfires on him.
Tim the Witch Hunter in Sabrina: The Animated Series since he was a half mortal and his fellow witches made his life miserable during his school years. He comes back with a vengeance with technology powerful enough to negate their powers and capture them. Even sticking their still living heads on his wall as mounted trophies.
The Lemons from Cars 2 were apparently made evil all because of this.
The Simpsons: In one episode, they discussed the origin of April Fool's Day. There used to be a time when people believed the year started in April. When it started changing, some people who adopted the new calendar mocked those who didn't. To exemplify, it was shown a flashback of a Flanders-like family mocking a Simpson-like family. The Simpson-like family did a Disproportionate Retribution by tying the Flanders-like family at a stake, setting them on fire and asking/chanting the trope.
Homer: And that's the story of April Fool's Day. Lisa: Dad, I was telling the story! Homer: Oh, right.
Kim Possible villain Dr. Drakken became an evil Mad Scientist after his college friends (one of whom was Kim's father) laughed at him for building fembots instead of finding dates for an upcoming dance.
In Western Animation/Ameri episode "Da Flippity Flop" Klaus begs Stan to finally place him back in his body after its discovered frozen and intact (Stan having placed him in his fish body years ago to prevent Germany winning the Olympics). It takes a while but Stan finally relents, only for them to discover his body has nearly completely decomposed in the meantime. Stan shows complete apathy to his situation, so Klaus finally cracks and knocks Stan out, switching their bodies. The rest of the family even support the prank due to Stan ruining Klaus' life, until they realise he intends to make the change permanent.