When I was about 14/15 I used to wait til everyone went to bed and then masturbate on my frontroom windowsill (it was wide enough for me to kneel on it) with the window open.
I would love the feeling of the breeze on my pussy. I don't know if any of my neighbours ever saw me. I didn't really think about it at the time, I guess I was a bit naive.
Also masturbated on a plane while the people next to me were sleeping.
On a bus.
In bed with my cousin, while he was sleeping. In bed with a school friend, while she was sleeping.
In the back of the family car on a road trip.
All around age 14/15, I was masturbation mad back then, not much has changed really!