"Are there hilarious rape jokes out there, twinkling and waiting to be discovered in the dusty old joke mines? Sure, that's possible, and we'll let you know when we hear one. Instead, when I hear a rape joke, what I hear is, "I don't care about women." I hear, "I want to laugh at women's concerns, and I want you to laugh with me." Rape jokes reinforce the idea that male identity is neutral and normal, and female identity is marginal and laughable. Terrorizing and marginalizing women is hilarious, and you just can't take a joke."
I'd also like to point out that the reason why certain men find rape jokes funny is that they aren't in the slightest bit worried that someday it will happen to them. If they got out of childhood without being molested by a creepy uncle and they don't go to jail, their odds of it are pretty low. So sure, if it's not a concern to them, they can find it hi-larious! Not their problem!
What I wish is that they'd think of (a) this happening to some woman they love, like their girlfriend or mother or sister, and/or (b) what if by some freaky horrible coincidence, they were going to go to jail and it was suddenly more of a possible reality for them. Then would they still be finding it funny?