When staying the night at a friends house. I was 12 and had discovered masturbation a year earlier. Couldn't sleep so I went to the bathroom. I locked the door and then made sure the second door attached to his parents bedroom was locked. Everyone was asleep and it was the first time I had jerked off outside of my own home. It was also the first time I had used aloe vera. I'll never forget how cold it felt on my red hot, hard little dick. I was so nervous but it was the first time I ejaculated and then I was so excited. After that night I became so much more ambitious and began experimenting with different lotions, objects and places. I'm not an exhibitionist and am not turned on by the thought of getting caught but I love the idea of jerking off and cumming in unconventional locations.
I've walked to the edge of a nearby golf course, stripped naked before walking out to one of greens, laying down on the wet grass and cumming in the middle of the night.
Have jerked off at abandoned rock quarries where I would go fishing several times.
In college I jerked off at several libraries on campus. Jerked off late at night in a biology lab I used to work in as an undergrad.
Found a mud pit about 10' across adjacent to a river I frequently fish. The mud was pure, not a shred of debris. I got naked, crawled in and started smearing it all over my body and began stroking my cock with mud. I finally just started fucking the mud and came in it.
Jerked off at my desk at work, during hours with about ten other people in the office, some only two or three cubicles away.
Excused myself from church service a couple times and jerked off in the bathroom.
Have jerked off under piers and pontoon boats while others played in the water or above.