This happened a few years ago.
So our school has annual trips to forgein destinations, this year it was Paris and France. So of course I took the opportunity to go. Once we were over there we were all split into rooms, now being the person I was I didn't have that many male friends on the trip so I spent most of my time with the females on the trip. I was always in and out of their rooms (doing nothing sexual at the time) every now and again I'd notice worn underwear on the ground or bras in their bags. I remember the first time I was alone in their room (I'd lost my wallet and asked for the card to get into their room to search for it) I decided I wanted to see what my friends (not really their names) Elleni and Stephanie had in their bags, now these two girls had some of the most spectacular bodies I've seen. So after rummaging through their bags I found 2 sets of what can only be described as the most beautiful underwear I've seen. I promptly laid back and started to m********* with it (it had been about 6 weeks since I last masturbated) after what felt like an eternity I exploded (my c** shots had always been above average from what I'd seen in videos) I had completely soaked these pairs of panties and filled the cups of the bras with s****, it took anywhere from 20-30 seconds of actual coming before I stopped. I was freaking out because now I'd come to my senses. These 4 items of underwear were soaking wet, And white on a black fabric is insanely noticeable, I grabbed panties out of their bags and cleaned up the bras, as for the underwear I'd originally c*m in I simply placed them back into their bags and left.
That was the start of my new fetish which carried on for another 2 weeks of being with these girls. I managed to do it to every girl I found appealing on the trip. And I was never caught doing it, although I believe they would of noticed with how much I came at times.
PS: I found my wallet in my room.