FACT: I only had one m/m experience in my life. Nearly thirty years ago I was in the Army in Germany. We were out on manoeuvers and this particular place had regular bathrooms with showers, stalls and urinals, we called them latrines. However we lived in those big tents.
One night I was on CQ (charge of quarters) for you non-military types, you stay up incharge of the company while everyone else sleeps. It was about three am and I was reading a graphic sex novel that someone had left at the desk. My cock was raging hard and I needed to jack, now!. I told the sergeant I was going to the latrine. It was late and I was alone in the latrine. I had never jacked in a semi-private place before, but my dick was stiff and I just had to stroke it.
I was there no more than 45 seconds, jacking away in front of the urinal and suddenly a soldier came in and caught me. I said embarrassed 'sorry man, but sometime you just gotta cum' as I stuffed my hard cock in my pants. He said 'why do you think I'm here' and pulled out his hard cock and started to stroke. I took mine out and we watched each other masturbate. I came hard with several ropes of cum into the urinal. He came hard as well. When we were done, which took about two minutes, we both zipped up and left. I saw him later and we gave each other a knowing look but never mentioned it.