World's meanest prank? :confused
I looked up a few of exactly what you want and I think it's one of those things where you would either have to be a doctor to tell what that specific x-ray is or if the target audience isn't a doctor you could take any pelvic x-ray and say that's what it is, even just altering it slightly. Printing it, which is what I think you're really asking, would be the hard part. You'd probably have to settle for a transparency.
BTW, the banana one is cool and awesomely creepy the way they added a spine to it.
-Rog