So I'm 18 and Ive never had sex. I'm straight, but I'm really curious about experiencing things with men. This guy Ive been talking online just asked me to join him and another guy in a threesome. I really want to try it, but I'm worried that for the rest of my life I'll remember that my first sexual experience ever was with a guy. I won't be able to donate blood, I would have to lie about it. What should I do?