Uhhh... why not sober? If you really want the tattoo, it's not painful exactly. The process of getting a tattoo is very exciting. I'd venture to say those of you who think you need to get fucked up to get one, don't have any tattoos.
You put a tattoo shop and the artist at legal risk if you're under the influence of alcohol or any drugs. I don't see the point in further feedback, so I'm going to close this one up.