I can't recall the name of a movie, maybe a TV series episode, where one character that was a cannibal started eating himself, so that after a while only the skull remained eating the last piece of flesh.
I know, it's creepy, but it should be a comedy or something like that.
Maybe from late 80's or early 90's, I tried googling it but the web is flooded with real life stories about cannibalism.
I'm not sure, but I think that the cannibal was some sort of savage chasing some people, he somehow put by accident a part of his body in his mouth and liked the taste, so he started eating himself.
I think the skull was shown at the end, before the credits, sucking the last piece of skin or flesh.
But again, it was funny, not creepy.