What's the difference between my wife and my cat? I can unsuspectingly put my cock in the cats mouth and it won't scream rape.
Jokes about rape aren't funny, and you shouldn't be making light of such a serious subject.
I dunno man, it's just a joke I heard somewhere. Trust me it works.
Making fun of rape victims is never funny. You should have some sympathy for the people who might have suffered assault in the past.
You need to relax its just a joke, if you can't take a joke don't take it.
There are some topics, like rape, that are never funny.  If you tell jokes like this to people who have suffered, they won't have the choice of whether to take the joke or not.