It depends on what you call "in public": discreet/risky sex in public places, or sex in front of others in dedicated places?

In the first case, I had sex in a car in the parking lot of the university, on a friday evening after class. An other time it was in a vineyard (she started to wank me while I drove. Safety first, I found a place to park the car on the side of the road). I fingered her at the beach, and some other day she gave me a handjob at the movie theater.

If you talk about dedicated places, I've done naughty things at the local gay sauna (I'm bi, in an open relationship). The most nsfw was probably a foursome in the steam room. It started as a regular 1+1, and other guys joined the band, one after the other. That was fun.