About this "The Simpsons" episode:

The Simpsons - Bart Sells His Soul is the 4th episode of season 7 and number 132 overall in the series.
Bart and Milhouse, after playing a prank to the church, are punished to clean up the organ pipes.
While they were cleaning and talking, Bart sells his soul to Milhouse for five dollars in order to prove him that there is no such thing as soul.
Bart begins to regret it when weird things begin happening to him such as not finding cartoons funny or not accepting hugs. Meanwhile, an encounter with the Hibbert family results in Moe converting Moe's Tavern to a family restaurant to make more money. The Simpson family eats there one night and after taunting from Lisa, Bart erupts and leaves to find his soul. It turns out that Milhouse had given Bart's soul to Comic Book Guy who in turn had sold it to someone else. It turns out that it was sold to Lisa, and she gives Bart his soul back. Back at the family restaurant, Moe loses his temper and swears at a child, resulting in him losing his customers and converting back to his tavern.