Wandered across a couple of such in my walks.
I think the best was, in Phoenix, while I was sitting on my porch, I got a full view
of a bj in a car below me. They must've wanted to get caught though - I was up
there blaring music as it happened. Seriously considered vidding 'em.
I don't think I've been caught, as such. Although in my younger days, we sure tried
a lot - public bathroom floor, school club office, classrooms, golf course, playground, et al. Some of
it was due to partial necessity (fucking around behind my PE's bf's back); others just for the random
thrill. One memorable one was right out in the middle of the street though, and I don't know if 'caught'
is the right word there; may well have just been seen.
Pretty sure folk were aware that I was masturbating in public libraries, in the early interwebz days.
More recently (though not all that recent) some chicky pushed me to go down on her on the dancefloor.
At least one person definitely noticed. It was pretty crowded though, so I'm not sure others did.
Nowadays, I'm a lot more likely to get caught pissing on some building.