The Parents Television Council is calling on Fox to edit a joke about rape in the upcoming "Simpsons"-"Family Guy" crossover episode, airing this weekend.  The PTC has issued an alert to parents and advertisers on its Twitter page declaring that there is "nothing funny about rape" and wondering out loud why "The Simpsons"-"Family Guy" episode would use it as a "punchline." 

The line appears in the special episode in which "Family Guy" character Stewie follows Bart Simpson's instruction in the art of making a prank phone call.  When Stewie dials up the owner of Moe's Tavern he tells Moe, his sister is being raped.  

Fox has yet to comment on the PTC's calls for edit.  Airing this Sunday, September 28th, the crossover episode kicks off the 26th season of "The Simpsons."