Alien Bruise.

So I have this big bruise on my butt...? Why does that always seem to happen to me?!

Mysterious bruises are the best. Usually I attribute them to alien abductions.

Well, wet Atlantis! An alien abducted my butt! Or, better yet...an alien implanted a tracking device in my butt. Or a mind-control device. Or a butt-control device...You know, I'm gonna stop here before I go too far with this one.