I haven't... but when I was in 9th grade I was the look out for my best friend and a guy from the detention center... so they could slip into the shop while the rest of the school was at an assembly. I don't know why they picked the shop... and I don't know why they didn't have a second look out for the back doors.. BUT as it turns out, the wrinkly, weird, old shop teacher came in the back door. I wouldn't be surprised if he watched for a while first. We all got busted for skipping the assembly, but I wasn't in half as much trouble as they were.
Film/video editing suites in college, public park in the middle of the field, while driving, festival camp grounds where everyone's tents are practically touching, lecture halls... and a little something right on top of the emblem on the basketball court at ASU. So, I guess that's a yes, HA.
In high school, during my sophomore year, my girlfriend at the time gave me a blow job during home coming (no pun intended) parade and during an orchestra ensemble. The whole school was outside during the parade and during orchestra she had keys to the instrument room. She was second chair for the violin and her part was over so we snuck in some good action.
I use to run a small one man retail store for a couple years. One day, out of the blue, my best friend's wife came in. She wanted to see what it was that I was doing. The next thing I knew we were in the back room and I was doing her in the back door. This went on for several years. We only stopped because we knew that if it kept going we would get caught one day.
It is still awkward when I'm over at their house and she and I make eye contact.
At school a couple of times. Our auditorium has rooms on the side of it that you can only get to from a ladder or the usually locked door. we went into the middle room we got some foreplay in and then just had sex.