Film Dope

Lisa gives up eating meat after a trip to a local petting farm. Naturally she is mocked for doing this, particularly when Homer, Marge and Bart do their "you don't win friends with salad" routine in the living room! Look out for an exquisit little scene featuring Mr. Burns and Smithers as a pig flies past their window.
Guest stars Paul and Linda McCartney

There is a reference to the film I Spit On Your Grave on a billboard.

See here for more details.