If anyone has ever stayed in hostels in New Zealand, then you'll know that all dorm rooms are shared (apart from in the biggest city, Auckland).
My biggest thrill is watching women masturbate, and I did have some great fun watching girls finger themselves under the sheets whilst they thought the rest of the room was asleep (or in some cases even when they knew I was watching!)
I learned also how to spot the more discreet women masturbate - trying to spot very slight movements, along with breathing patterns, and working out where the hands must be positioned under the sheets.
Occasionally I would do it too (impossible to be quite so discreet when you're a guy unless the rest of the room were turned the other way).
There were so many instances of this happening (I stayed there for a year, being in hostels about two months in total), so it's difficult to remember every occasion, but I'll try to relay a few.....
I came back from work one night and there was a couple in one bed, but when I settled in the girl left the guy and went to her own bed. She then proceeded to give herself a marathon clit rub. I could see quite well as the curtains weren't shut properly and there was light shining through the window. She went on for hours, crashing her knees into the side wall as she had an orgasm. At one point I rubbed my cock so she could see. Not sure if her boyfriend was asleep the whole time. I'm pretty sure she was watching me, and I came into my boxer shorts after 10 minutes - just couldn't hold it in much longer, but it was a great cum. After I came she just kept going and going. I fell asleep and when I woke up she was still at it. Quite attractive too - German or Swedish I think - she smiled and said hi the next day as she dashed off.
I shared one night with two German girls - was speaking to them in the lounge for a bit before they went to bed. I followed an hour or so later, and felt ready for a wank, so I did, and deliberately made it not too obvious what I was doing, but obvious enough for them to guess if they were paying attention. One girl I think started masturbating but I was not 100% sure. I gave a soft moan when I came. The next morning when I woke up the same girl was definitely masturbating and I could see clearly with the sun shining in. She was facing away from me. I started too, making squishy sounds as I rubbed my cock up and down. When she heard this she started going faster too, then I went faster. She kept going and after less than a minute I came and let out another little moan. Seconds later she orgasmed too and let out quite a long loud moan. Then I fell back asleep soon after. When I woke up they were both gone....
One young pretty girl just absolutely went for it one night in a room of 4 along with myself and an older woman with her 12/13 year old son in the room - she left very early in the morning so presumably didn't have to worry about being spotted again! She rolled over a lot, didn't make much noise at all with her breathing, although there were a number of squidgy sounds, ending with her legs moving around a lot as she hit orgasm. Couldn't say for sure but I think the young son was watching too.
Overall I'm sure that well over half the girls I shared a room with masturbated while in bed - that makes probably around 25 in total. Some nights I stayed it was all guys in the room.
Would be interested to hear from girls who have masturbated in shared dorms, and if being in company in the room gave them more of a thrill, or whether they were just desperate for some relief!
Who knows, maybe this will encourage some people to hostel round New Zealand! It's the best place I've been (not just for the reasons above!)