Yep, I have to agree with Sploke on this one. It may be hard, especially if you have a shyness to ya, or worry about hurting someones feeling. I know that can be tough sometimes to say something to someone when it is a touchy subject...but he was wrong, and if you do not say something to him or someone...it most likely will happen again no matter how hard you try to ignore him.
Sorry to anyone here that may take offense to this...but guys are guys, they are going to do whatever they think they can get a way with. If you say nothing, he will think you didn't mind and he will do it again...I'm not trying to scare you or anything, but guys can be very persistent and they are not good at reading "signs" such as just ignoring him. I know this for a fact, they can be very aggressive and hardheaded and sometimes even if you do tell him to stop...they wont. If you do tell him it was wrong, made you feel uncomfortable, and you do not want him to do it again, and then he still tries, knock him on his ***...and then, you HAVE to tell your family....even if it means the death of him because you do not want to have to deal with the emotional crap that could come from all this in the end...believe me ok, just tell him it is the only way really.
If you wanna continue this in PM, then send me one...I'll listen, and talk with you about it more