During one summer at the beginning of my puberty we often spent the day time by the lake near the village. One of my friends was dating a local girl, kind of next door one, not bad but little bit bigger than he was. He had happened his first experiences with her, like touching, petting and so on, they didn't do anything really sexual (as far as I know).
We shared some of his pleasures once. We were all swimming together in the lake-he, his girlfriend, me and two other boys, all age of 14-15. At one point the couple was hugging very intensively and we started to swim and then walk around as it was some kind of ritual dance. We were softly pressing them together to get closer to each other and this touching them both went into touching the girl gently on her legs, back and neck. He had undone the top of her swimsuit and by the time we could see her bare breasts we all had erections. It was clearly visible under the water by all of us and I think this was the reason she let us do all this. She liked the idea of being surrounded by four horny boys just because of her. As for myself I accidentally touched her with my penis several times on her leg and I think this happened to all of us. We continued to dance around her, sometimes also touching her tits, but then she started to feel cold, so she went out from water. We couldn't because there were several people and kids around and we all had hardons.
One of the guys I had masturbated with before suggested to go further from the shore and jerk off there. I and one more boy joined him, the rest just stayed where they were. We went little more out from their sight and jerked off standing in a circle. I was so horny from all that happened that I finished in like a half minute, maybe less.
When we went out from the water she asked us what we were doing there, so we admitted we were so aroused by her we needed to jerk off. She was very much surprised and then asked her boyfriend and the other guy why they didn't join us. It sounded like she was sad that she wasn't arousing enough for them too. Later her boyfriend told me that day she gave him the hand job for the first time because of all what we told her, as she wanted to see how it works.