I assume you are female, right?
Some guys will say that you can't be straight and bi-curious, but I think of sexuality as a continuum, and if his sexuality is somewhere in the middle, then I don't know why he couldn't be curious about other guys.
Here is the thing though: if he is a teenager/early 20s, he is at the peak of his sexual interest, and I think with all those hormones coursing through the body, a lot of guys would stick it ANYWHERE to get an orgasm.
Still, if you intend to pursure a sexual relationship with him, be VERY careful. HIV infections are on the rise in the homosexual population, and you will definitely be at increased risk. Educate yourself, practice "safe" sex, and be sure this guy is REALLY worth taking the chance, and know if he is trustworthy. Don't be impulsive.
Relax... I'll need some information first. Just the basic facts - can you show me where it hurts?