In the opening scene, Homer tries to vote for Democratic Senator Barack Obama in the 2008 American presidential election. However, the voting machine is rigged to turn his vote into one for Republican Senator John McCain. After six attempts to vote, Homer heads out to report the mishap but the machine sucks him in and kills him. t then spits out his corpse and then Jasper puts an 'I Voted' sticker on his head. The scene then zooms out to view the title and opening credits.

Bart buys Lisa a Malibu Stacy convertible as a Christmas present. However, the car turns out to be a Transformer. The robot transforms all of the technology in Springfield into robots so they can wage war with each other. Just as two machines prepare to face off, Marge asks why the robots war with one another; as it turns out, they can't even remember. Thanking Marge, the two sides declare that they will work together to conquer the human race, and use the residents of Springfield in a game of table football.

Homer takes Maggie to a daycare and encourages her to enjoy a mural featuring Krusty the Clown to make her feel better while she is away from her parents. Krusty arrives to have the images of his face sandblasted from the mural, as his likeness is trademarked and used without his permission. This upsets Maggie and an outraged Homer shoves Krusty in retaliation, sending him flying into a wood chipper where he is shredded.

Homer is later approached by businessmen who have heard of his deed and explain that the likenesses of dead celebrities can be put in commercials for free. They manage to convince Homer to start killing celebrities, and he kills several, including George Clooney, Prince, and Neil Armstrong. In heaven, the dead celebrities are outraged by these exploits. Krusty convinces the dead celebrities to descend from heaven and stage an attack upon all those who benefited from their deaths, striking in the midst of one of Homer's parties. Krusty kills Homer by blowing his head off with a shotgun. However, Homer gets revenge by locking the celebrities out of heaven before they return.

Milhouse waits in a pumpkin patch for the Grand Pumpkin on Halloween (which Bart made up) and Lisa decides to stay with him. After Lisa sees everyone at school having a Halloween party, she grows tired of waiting and leaves in frustration. Milhouse starts to cry and his tears and childlike belief bring the Grand Pumpkin to life. However, the Pumpkin is appalled to find that his kindred pumpkins are being carved up on Halloween, and vows revenge.

He devours Homer as he carves pumpkins, then marches to the school and eats Nelson who threatens to stab another pumpkin, then eats Groundskeeper Willie after being offered a pumpkin seed. Realizing that Milhouse can bring things to life by believing in them, Lisa tells him about "Tom Turkey," a symbol of Thanksgiving. Milhouse starts to believe in Tom Turkey, who comes to life and kills the Grand Pumpkin, freeing everyone he ate. However, when Tom Turkey learns that people eat turkeys on Thanksgiving from Bart, he vows revenge and starts angrily chasing children around the school, devouring some of them whole as Marge wishes the viewers happy holidays.