When I was young, on a long road trip, I jacked off under a blanket into a sock while my whole family was there.
I also came outside near a bus stop. I was within site of the bus stop, but my back was turned to it. There were also several buildings (with windows with a lot of people) to my left, but a girl I knew (who I hated) who was the "no matter what I always love you" type (we were both 15) stood between the buildings I.
It was actually a funny story. She said she wasn't interested at the time. I asked if I could reach under her shirt and grope her breasts. She let me, and me groping her a bit turned her on enough that she wanted to see it now. I was horny now, so I pulled out my cock and she put her hand on it. I then learned that she didn't know how to give a handjob.
I grabbed my dick and jacked myself off in front of her. She hadn't seen a guy cum before, so she was absolutely amazed. It shot my ego up several notches, but due to other circumstances I don't feel like going into, that was the last time I talked to her. It remains, to this day, the farthest I've gotten. :/