This happened yesterday (real story)
I was at the beach with my recent group of friends. There were three of us guys and eight girls. We had laid out towels near the shore, and the guys were playing with a ball. The girls were jokingly whistling at us, as if telling us to keep doing our "guy activities." One of my friends knew I liked one of the girls, so at one point he said out loud, "Anne (the girl), look at your future boyfriend," and the guy pulled down my swimsuit in front of them and the other girls. My physical reaction was first to try to grab my swimsuit early so they wouldn't pull it down, but I was late, and there I was with my penis and ass completely exposed. What came out of me immediately was yelling "NO!" They started screaming and laughing a lot, and I was dying of embarrassment.