Forced by girls

When I was around 13 a group of girls decided to get me to join in a game. They were playing a kind of truth or dare game and I hadn't realized it straight away but I was to be their victim
They dared me to lay on my back and see how many of them could sit on me at once.
No problem I thought
there were 5 of them sitting on my arms, legs and chest and I seen realized I was well and truly pinned down. No way could I move.
Then one girl dared the one sitting on my chest to undo my pants.
I almost died, I didn't think she would do it but I was wrong.
Not only did she undo them but she pulled them down and the other girls sitting on my ankles helped.
Then there was a dare to see if one of them would remove my underpants.
I dont know what others would have done but I gave up protesting and let them.
They pulled off my underpants my dick becoming completely exposed.
They were all taking a good look and I realized it had started getting hard.
I couldnt actually see it myself but I could feel that I had a full on boner and this was the first time anyone else had seen it.
The next dares were to see who would dare to touch it and they each did so in turn. One by one they took it in their hand and felt it. There was even a remark about how it was really hot and throbbing.
I was overcome by embarrasment by now and practically begged them to stop.
I had to promise if they let me go I wouldnt tell anyone and that if anyone should want to see it again I was to show them
I agreed and when they let me go I went straight to the toilets where I masturbated having the event so fresh in my mind

I think it's one reason I became a bit of an exhibitionist

I'm curious if anyone guys have had similar experiences or if there are girls who have done something like that
I can't believe that my experience is unique