Simpsons Season 5, Episode 7: Bart's Inner Child

Marge realizes that she is no fun because of her constant nagging and seeks help from self-help guru Brad Goodman, who then uses Bart's irreverent attitude as a new example of how people should behave. The entire town of Springfield begins to act like Bart, who at first enjoys things but begins to feel that his role as a troublemaker is usurped. During the inaugural "Do what you feel" festival, several things go wrong and the town decides to stop acting like Bart.