When I was in college, my girlfriend and I were in her dorm room getting hot and heavy. She kicked off her sneakers and pulled her pants and underwear off, signaling she wanted to have sex. I unzipped, took out my Johnson, slipped a condom on it and entered her. She reached around and pushed my jeans and boxers down to my thighs and started rubbing my butt. It was right around that moment that her roommate and a couple of her friends came strolling in the room. They all gasped. I stopped, not knowing what to do. What would be more humiliating? To quickly pull up my pants and roll off my girlfriend? To stay still until they left? Or to just keep going? My girlfriend said, "Why didn't you knock?" Her roommate said, "I didn't know you two were in here. Go ahead, we'll come back later." They left the room and she and I finished what we started. It wasn't until later that I relized that, although I had certainly been embarrassed by the girls seeing my ass, I also found it kind of a turn-on.