Tattoos are sexy. I mean, I don't want any. But I think it's cool that other people have them.
Some people have power over tattoos. They can use tattoos to kill, or to get new powers, or even divine the future. Others just use them to increase their Awesome bad assery, making them self-made Awesomes (even if someone else designs the tattoos, people usually have a lot of discussion with these artists about what is right for them).
Unless you're drunk when you get one. In which case, what are you even doing with your life?