First of all, I have two words for you: regrown penises.
Which brings me to a question.
Why rabbits? I mean, as far as I know, they aren't endangered and clearly don't have reproductive issues, thus the saying "fuck like a rabbit".
I don't know, couldn't they have tried to regrow another animal's penis? Maybe one that needs help, like the Giant Panda? Or a polar bear?
Oh, and on my feminist rant side: WTF! Science makes it easier for men to knock up women. When are they gonna make a penis that shoots blanks? What about MALE BIRTH CONTROL that doesn't involve clipping tubes?