This happened when I was 14.
We were having some family friends over, and I was sitting across from their daughter who is the same age as me. I was just sitting there listening to the conversation when I felt something rub my feet. I look over and we lock eyes. For me a horny 14-year-old boy this was the most incredible and exciting sensation. It was so weird to be making a connection when completely on opposite sides of a table.
Anyway, right after dinner I notice that she had dashed of to the bathroom farthest from the dining room. So I went back there too (my room is in that same hall) and stood at the bookshelf in the hall right next the bathroom door, all the while listening.
All the sudden I hear a little moan, kinda like letting all the air out. Then I hear this squish sqash, I am like, oh my god this girl that I have the hots for is masterbating quite noisely less than three feet away. I stood right next to the door and jerked off as she was getting off. As I listened I heard her have an orgasm and that took me over the edge. I quickly pointed my dick into my underwear so as not to make a mess, then slipped into my room.
Less than a minute later she came out of the bathroom, very flushed and a little suprised that I was in my room instead of out with everbody else. She is still one of my good friends today but I have never told her about what really happened.
Thanks for reading my story, comment if you liked it or had a similar experience!