You stupid lucky bastard. Didn't you ever figure it out? One of those girls liked you and wanted to see you naked and probably asked her friends for help. She probably frigged herself to a nice cum thinking about your naked body. There is nothing sexier than have a bunch of people look at you when you are naked and for you to get away with it without getting into trouble for exposing yourself. Wish somebody had done that to me.
Now you have a bunch of girls dying to fuck you. !Enjoy!
Some boys did that to me in a party. As usual they pick the youngest one, because his the most vulnerable and that happed to be me. Only thing that didn't come off were my socks. Fortunately it happed indoors in front of some girlfriends and not outdoors where everyone could see me. That would have been horrible and way more humiliating.