The Exorsister!

The Exorsister! is a Bart Simpson's Treehouse of Horror story featured in.

Synopsis
Lisa starts acting unusually and is revealed to be possessed by the spirit of Madonna.

Plot
Lisa becomes increasingly obsessed with Madonna, even dressing up as her in a role-playing game. One day when the Simpsons are hosting a lemonade party, Lisa, who has been feeling unwell, spills lemonade on the floor and randomly starts to sing Madonna songs. Marge takes Lisa to a number of doctors when she is unable to stop behaving like Madonna but no-one can diagnose her with anything. As a last resort Marge turns to Reverend Lovejoy, as she now believes Lisa is actually possessed by the spirit of Madonna. Reverend Lovejoy visits Lisa in her room as she is now under Madonna's full control. After a number of unsuccessful attempts at exorcism, he shows her a negative review of her acting ability and Madonna is forced out of Lisa but instead possesses Reverend Lovejoy as he leaves the house.