Living on a farm, I had the gist of it down pretty well. Parents gave me "the talk", but never explained what an orgasm was or what it felt like, or when you would know when it happens. So I didn't know.
In school, we had the sex ed class and a teacher who was way cool and extremely difficult to embarrass. We managed to do it, though. Our class was co-ed, so there was a lot of whooping and hollering as everyone either pointed out or noticed things about others as they were being explained. It was a hoot!!! He explained everything except the orgasm part. (what it felt like/when you'd know it happened.) Still I didn't know. I got everything else.
So now I'm 14, and my girlfriend jumps me. It was the first time for both of us. She has her orgasm first, (which was amazing considering the really rough start we had) and I just thought she was really getting into this. When my orgasm hit, I didn't know WHAT happened.

As soon as it was over, I thought I was "broke", and that I needed to go see a doctor. My best friend was in the house, so I ran to him, still naked, and told him what happened. He just busted up laughing and told me that's what is supposed to happen.
Who knew?
