My girlfriend wants tattoos and piercings, I can't stand them.?

Dude, TELL HER THAT. Tell her that the thought of her getting body modifications makes you uncomfortable. If she won't budge, then too bad; it's her body, and she can do what she wants with it. If you don't like her body modifications and that changes the way you feel about her, then tell her. Communication is key to any relationship; you can expect to solve problems without talking about them.