Simpsons-Family Guy crossover episode under fire over 'troubling' rape joke

"Hello Moe, your sister’s being raped."

(FOX)

It has yet to even air, but the Simpsons – Family Guy crossover has already got some up in arms over a joke the punchline of which is "your sister's being raped".

The joke featured in the trailer which debuted at Comic Con in July, but is getting talked about now as it seems Fox won't be editing it out when the hour-long special airs in the US on Sunday.

It starts with a familiar Simpsons gag set-up:

"Moe's Tavern, Moe speaking."

"Uh yeah, I'm looking for a friend, last name Ki-Bum, first name Lee?

"Hang on I'll check, hey guys do I got a Lee Ki-Bum, do I got a Lee Ki-Bum?"

But then Stewie tries his hand at the prank:

"Hello Moe, your sister’s being raped."

Full trailer:
This is far from the most controversial joke Family Guy has aired, but it seems to be causing outrage by proximity to the usually fairly moral Simpsons.

Tim Winter of the Parents Television Council (yes that's a real thing) told AP: "I was blown out of my shoes when I saw the scene with the rape joke in it, It really troubled me."

He said he had written to creators Matt Groening and Seth MacFarlane asking that the joke be removed, but hadn't received a response from either them nor Fox.