Well, that's the thing. Some people find rape jokes funny, in certain situations. And those people are only sometimes misogynists - more often they're just kind of adolescent, and it's the shock value of the joke that causes the giggle (as with all the "minority"/othering jokes out there).

This is why I'm not stating rape jokes aren't funny, since they clearly are to some people (though it'd be bloody great if they weren't) - I'm saying rape jokes are never funny to people who've been raped, and as a valuable service to those people, it's best to avoid telling them just in case.
If it's brokenless, don't suffix it...