Every time someone asks me to get a tattoo, I always say to them, "A tattoo? Hellooooooooo hepatitis B!"
Not that I have anything against tattoos - hell, I've dated a few girls with tattoos - but working at a hospital has made me somewhat OCD about sterile conditions when it comes to needles.
Anyway, if a gun was put to my head I'd probably get a rune design from a Suikoden game. Niche enough that most people will just go 'huh, that's a cool design' without knowing what it is and common enough that gamers would go 'hey, I know that thing!'