I am in the British Army and often go on exercises with my mates where we have to stay in tents - usually about ten of us in one tent. Obviously, if we are way for a few days, everyone gets the urge to wank and the camp beds are even called wanking charots, so everyone knows that everyone else is at it!
One time, I was really horny and this younger lad in the bed opposite me was being prretty obvious about his wanking, because when a Landrover parked outside the tent with its engine still running, he wanked even harder so that it was really obvious. His hand or dick must have been rubbing furiously against his sleeping bag. Well, I started to make my jerking obvious too and he stopped and then started again even faster. I got really turned on knowing he knew I was wanking, and decided to unzip my bag and lay there with my boner sticking into the air and jacking. There was enough light for him to see this, and he did the same. I spunked my wad there and then and felt dead guilty about it. He stopped and I saw him wiping himself with a tisue, which he threw over to me. It was soaked in cum! Nobody else seemed to notice and he said nothing about it the next day