When I was about 16 I was on a week long school camp. We had rooms that we shared with one another, the beds were either side of the room with a small table between. One night I woke needing to pee badly and as I opened my eyes and started to focus I noticed that the girl in the bed across from me was moving her sheets. As I became more awake I could notice that she was breathing heavy and that her legs were spread under the sheets. It dawned on me that she was masturbating. I was really busting but was to embarrassed to get up incase she knew that I knew. So I decided to wait until she finished and went to sleep again.
She was taking her time and her movements were making me horny as I could see her touch her breasts and then as she moved and her leg came out from under the sheets. I could see her crotch. She was rubbing through her panties. By this stage I was getting desperate and had my hand between my legs but still couldn't move incase she saw me awake. She seemed to be enjoying it and had her hand down her panties now as well. I was getting wet but also desperate and began to feel myself squirt a bit.
Finally I couldn't hang on and began to pee myself, as I was wetting myself she came and with my hand still on my crotch I could slide a finger up and down between my lips. I was totally wet and the bed was as well.
The next night I awoke again for the same reason but this time she must have noticed. I was busting again but didn't say. She asked me if I saw what she was doing and I said no of course but she didn't believe me and said that i should give her the same opportunity to make it fair. She came over to my side and got in bed with me, put my hand between my legs and started to move my hand. I told her I had to pee and she said not until we were finished. I was getting horny, very horny and started to rub myself. We were very close in bed and on our sides facing each other. I could feel the back of her hand against mine as she was rubbing herself. I was nearing orgasm and pleaded for her to let me get up. She just put her hand on mine and kept me rubbing. I said to her that I was coming but I would pee as well. As my orgasm neared my arse cheeks clenched and then I came and then just peed again. I moved my hand to put hers between my legs as I was peeing and rubbed back and forth over it and came again.
The rest of that camp we would each watch each other in the bathroom peeing and masturbating. To this day I often pee and masturbate through my panties and a few times have done it with my boyfriend.