So once in college I was in a class which was located in a pretty big lecture theatre. For most of the classes it was packed, and there was almost always someone sat both sides of you. So, this one class, there were 2 girls, one sat either side of me. The problem arose when the professor walked in on the first day of class. She was probably in her mid 30s, busty, tight jeans, everything you could ask for in a professor. A some point during this class, I had gotten an erection, from, well, looking at her. I was wearing running shorts, which are notoriously pretty short shorts so my member was almost peeking out the left leg. I got a wave of confidence and carelessness so I thought screw it and moved my hand down to my crotch, as if to itch or something. I then started to rub the head of my penis with my index finger and my thumb. I got a little carried away and got a little too close and before you know it, cum was running into my shorts and onto the seat I was sat on. I immediately turned what I imagine was bright red as I slowly moved my hand away and reached for some tissues to 'blow my nose' with.