Bart's Little Fantasy is the thirty-seventh Simpsons short and originally aired on The Tracey Ullman Show February 5, 1989.
Homer and Marge force the kids into a mess they have to clean up. Bart slacks off and tells them a story where children are the parents and the parents are the children (The story is similar to what happens in the beginning, except the roles have been switched so Marge is Lisa and Homer tells a story like Bart only for Marge to respond with "Forget it!") Then Homer and Marge walk in the room and catch Bart red handed for not helping Lisa and Maggie. Homer angrily tells him that if he doesn't help his sisters clean the room, he'll be forced to go outside and mow the lawn. He shoves Bart outside and makes him mow the lawn. Lisa tells Maggie they lived happily ever after and they wave at the scowling Bart through the window as he is forced to mow the lawn.