This is one of several Simpsons episodes which are considered anthology episodes that features mini-stories.
When a motorist cuts Homer off and he swears revenge on the driver, Marge, Lisa, and Bart tell legends of revenge:
In prerevolutionary France, Homer plots his revenge on Moe after he frames Homer for treason. The geeks develop a glove to inflict punishment on the bullies, but Milhouse has his own enemies list. When young Bart Simpson's parents are murdered in Gotham City, he becomes Bartman in an attempt to locate the killer.
While the Simpsons are riding in their car, they are cut off by the Rich Texan. Homer gets outraged, chases the car and swearing revenge. So his family tells three stories of vengeance, hoping to convince Homer that revenge is not a good idea.
Moe breaks up Homer and Marge's marriage by framing Homer as an English traitor. When Moe marries Marge, Homer, now in a French prison, swears revenge. His cellmate, Mr. Burns, tells him to find treasure through a tunnel that he dug. Homer finds the riches and becomes the Count of Monte Fatso. Five years later, Homer invites Moe and Marge to a party at his mansion, where Homer kills Moe in a homemade revenge machine. However, Marge angrily rebuffs him for killing Moe, because without him, there's on one else to take care of her new triplets. Back at the present, Marge tells Homer that revenge can only lead to misery and sadness, but finds that Homer has been listening to a Jamaican music station instead of her story. When she tries to remind him, Homer grabs his bat and yells "Revenge!"
Revenge of the Geeks
Lisa's story, based on the film Revenge of the Nerds, revolves around Milhouse's campaign to fight back against the school bullies, and the consequences when he goes too far.
Tired of being bullied by Jimbo, Dolph, and Kearney, the geeks plan their revenge. In the science lab, Martin reveals his latest creation, The Getbackinator, an awesome gagdet of mass destruction. Milhouse - the only geek with any hand-eye coordination - uses the weapon on the bullies, but then begins attacking anyone who has ever wronged him, including Martin (for accidentally hitting him with a shuttlecock), Richard (for being more popular with girls), and Wendell (for giving him "Chinese cuts" in the lunch line). Milhouse even shoots a kid who had never done anything to him, claiming it is 'prevenge'. Milhouse gives Groundskeeper Willie an Ultimate Noogie which cuts his head off. Lisa eventually convinces Milhouse to stop, and he reluctantly throws the device away. Nelson then returns from an absence due to mumps, finds the weapon and turns it on the geeks. Homer likes the story because it has what he likes in a story—an ending. Lisa says the moral is that revenge can make you as bad as the person who harms you. Homer argues the moral should be "never let go of your weapon".
Bart recounts Bartman's "origin story", based on Batman's origin as revealed in the film Batman Begins.
After leaving the Gotham City Opera House, Homer and Marge are killed by Snake Jailbird in a dark alley. Homer pleads Bart to avenge him in "a flamboyant, impractical fashion". Bart does as his father says and swears revenge on Snake, giving birth to his superhero ego, Bartman with the help of his grandpa. He flies around Gotham City, defeating enemies on his way for justice. When Serpent, Snake's alter-ego, attempts to steal the "Stealable Jewels of the Orient" from the Gotham Natural History Museum, Bartman arrives, saves the Jewels, and kills Serpent by impaling him on the fangs of a snake statue. In the end, a reporter (played by Lisa), reminds Bartman that the Serpent's death will not revive his parents. Bartman agrees, but adds that he now feels better and has gained zillions of dollars and freedom from his parents, then goes home to his mansion to exercise while being fawned over by a beautiful woman. Unlike the first two segments, this story implies revenge is satisfying; nevertheless, while Bart was telling the story Homer reconciled with the Rich Texan after discovering they are both from Connecticut.
At the end, the screen reads "Dedicated to all who died in the Star Wars films". The list includes: Darth Vader, Darth Maul (Though he didn't really die till Twin Suns), Greedo, Uncle Owen, Storm Trooper #5, Jango Fett, General Grievous (Droid), Storm Trooper #22, Dak, Obi Wan (Ben) Kenobi, "Whoever Jimmy Smits Played" (Bail Organa, which means he was likely on Alderaan when it was destroyed in A New Hope), Jabba the Hutt, Sy Snoodles, "Unfortunately, not Jar-Jar Binks," and "everyone on both Death Stars when they blew up". (This list is incomplete; it misses Qui-Gon Jinn, Count Dooku, Yoda, Mace Windu, Emperor Palpatine, and many minor characters. Also, Sy Snoodles was not shown to die in any movie.)