Rabbits

I hear they keep them on leashes so they don't rush into the audience and kill innocent bystanders.
Sci-Fi authors will tell you that the next big breakthrough in medical technology will be the ability to grow our own organs for transplants. In the idealized future, you'll have a heart or kidney cultured from your own cells on hand for whatever emergency might come up. Well, scientists have taken another step closer to creating functional replacement tissues, detailing the creation fully-functional penis part replacements in rabbits in a paper published Monday in the Proceedings of the National Academy of Sciences. . Yes, I did say penis part replacements. They are serious. Hey, if you're…