i'm not sure if this counts as behind the ear, nor am i sure this is an issue anymore... however i got this done:

Its not directly behind the ear, but it IS slightyl above and behind the ear... all i can say is that no migraines resulted from this tattoo (and i'm severely prone to migraines), and it really didn't hurt anywhere except on the hairline because it would pull the hair that wasn't shaved. besides that, it really didn't hurt. it was done in about three hours with one break so we could smoke.
pain is relative. if you really want something, you'll find a way to deal with the pain. everyone thought i was gonna have to be held down to get my head tattooed and i was just fine.