When I was a member of the NZSO, if there was a concert I wasn’t involved in but I wanted to hear it, I would occasionally sneak out into the audience from backstage.
... got a tattoo you regret?
No, I haven’t been tempted by tattoos. Besides, my pain threshold is near zero, and so I’d be like Phoebe off Friends, who chickened out after one dot of ink on her arm, which she then explained was a minute illustration of our planet.
... peed in a pool?
Never. God knows, there’s enough gunk in the average swimming pool without me adding to it. Besides, I prefer to swim in the sea. I’ve never peed in there either. Same argument, really.
... written a very personal email to someone and sent it to the wrong person?
No, but I’ve had a similar thing happen to me. I was having some "administrative" difficulties with an orchestra I was due to conduct. One of the staff inadvertently sent me an email meant for her colleague, complaining about how forthright and arrogant I was over a particular matter, which in fact had been mishandled by her. I was proud, and also consequently gratified by her fawning apology after I had pointed out the error to her. The matter was duly resolved.
... accidentally dropped the F-bomb during a lecture or an important meeting with high-ups?
Occasionally during lectures of a more passionate discourse. The students appeared not to mind, although one must always be careful in these litigious times.
... played a practical joke on someone and felt guilty because they still (to this day) don’t know who did it to them?
The only major practical joke that occurs to me was during a Cambridge Music School in 1977. A good friend’s tent was erected next to a large tree stump. During the evening when he was absent, some of us removed everything from his tent, stored it safely, and then re-pitched the tent around the tree stump, with nothing more inside than a lit candle on the stump itself. We hid and waited for his return. His reaction was delightful. He literally rolled on the ground laughing.