Take a look at this couple with armband tattoos and see if you can tell which one is real and which is a fake.  Then come back and read the rest of this post.  A good quality waterslide temporary tattoo can be very hard to distinguish from a real tattoo. 

Actually, this was a trick question.  Both of the tattoos are temporary tattoos.  Live your fantasy for a few hours or a few days.  There's no pain, no blood, and no lifetime commitment.