Great story, Cooker!
We were lucky with our boys, and our girl. No incidents of that sort, but other types which were not easy. The teen years are dangerous and the kids are very headstrong. I think the best line of defense is to do your best to keep the doors of communication open so that they feel comfortable to come to you with their stories. If your son is embarassed that hopefully means that he will be more careful. Perhaps he was egged on and taunted into this situation. Peer pressure is awful at this age. We always always stressed to our kids that if they ever got into a situation that they could not handle, no matter how ugly it had already become, we would come to their rescue and ask no questions...if only they would please call us and let us get them. My father did that for me and I never forgot it. I was so incredibly embarassed, but he came to get me. They need to venture out and make mistakes, but they need to know that we are there for them no matter what, too! Consequences can be a very useful thing, and we certainly used them. But love is the strongest, at least, in my belief.
Good luck! Keep loving arms wound around them and it won't be so bad!!
Marguerite