Anticipating a bloody Clint Eastwood-Lee Marvin shoot-'em-up, Bart and Homer are horrified to discover that their video rental, Paint Your Wagon, is actually a musical. Several song and dance moments from seasons past are recalled.
Homer rents the family the movie Paint Your Wagon. He and Bart expect to see a violent Western starring Lee Marvin, Clint Eastwood and someone who appears to be Lee Van Cleef; the truth is, it is a musical. This causes Homer to dispose the tape and condemn singing, but Marge says that Homer often sings.
Ultimately, this allows clips of the following songs from these episodes to be shown:
The family's singing motivates Snake Jailbird to come in; he is bothered by the Simpsons' singing and constantly tries to kill them, ironically doing his own singing. During the credits, Snake's voice can be heard trying to prevent the theme music from playing in the background, having grown annoyed of music over the course of the episode. At first, when he wanted to kill them, he didn't have a gun, so he left to get one. Later, he came back with a gun and pointed it at The Simpsons but had no bullets so he left again to get ammo. Near the end, he was finally going to kill them, but the singing ended and he had no reason to kill them so he left again. But when Marge was pulling down the banner, she was humming the main theme, so Snake fired a bullet, breaking the glass to which Marge remarked that she was done singing (or humming).
During the end credits, Snake is heard shooting, which causes the theme song to stop, then play very quietly. Snake still hears it, and shoots again. When the Gracie Films logo is seen, he even shoots the music there.