I've tattooed several men's cocks. Two spiders, "Suck it", a rose, racing flames on the foreskin, a spider web on the head, a dagger and a bird in flight. Always wanted to do a snake or cigar band. Don't get your girlfriend or wife's name on it. A friend did it and his 2nd wife hated it.
Be prepared for comments from strangers in locker rooms, the gym, etc. Might want to put on a temporary tattoo on your cock for a month and see how YOU react to other people 's reactions.
You're probably not going to have to worry about getting an erection while you're getting tattooed. It's not going to be too excited about seeing a needle coming toward it. That seems to be one of the big concern for my clients but I've never seen it happen. Good luck and hope you find the right artist.