Admittedly I didn't see the show, I cannot comment on the context of the joke.
But based on what I've read, obviously the subject matter is a serious one.
Having said that, anyone who's been raped will not find it funny.
He or she will find it offensive.
Women who've been subjected to sexual assault will not find it funny.
Anyone who's been bullied in one form or another will not find it funny either.
True, it was just a joke and it was all for laughs.
But like any form of entertainment, comedy can be in bad taste or good taste.
I think this one falls in the former.
What saves the comedian on this issue is that there is free speech in this country.