I was in 6th grade. The tables were shared - 2 people per table, and the sides and back were surrounded by metal, so no one could see anything. I wasn't really close friends with the dude next to me, but I wasn't interested in him at all. I just happened to get a random boner in my basketball shorts and was horny enough to start playing with it through the leg opening. I was just touching it and playing a bit, wasn't full on jacking or planning to cum or anything. Next thing I know my roommate leaned back really quickly, and as a reflex I looked over to see and he was looking at my dick. I put it away and pretended nothing ever happened and we never talked about it.