Not long after we got together, wife (gf back then) and I got caught by the police.
Wife was somewhere between 18 and 19 at the time, I'm 5 years older.
We had our car parked at a big parking lot of some stores.
It was a known place for young people to have sex in their cars at night.
Little did we know that the police checked out the parking lot from time to time.
So while we were fucking in the back seat, my wife on top riding me, a flash light lit up the whole car.
At that moment, it scared the crap out of us and adrenaline was all over the place
Luckily for us, they just urged us to get dressed and move along.
Next they want knocking on the steamy car window of the next car parked a bit further.
Afterwards we could both laugh about it and my wife did admit she had found the experience to be a bit thrilling.
Being watched while having sex.
In the 15+ years we have been married now, we have been naked in public lots of times (nude beach, nude swims, public sauna center) but never really been caught. We did meet people we knew while "legally nude" and we are also joined often by my wife's sister and her husband.
And to keep things exciting, we have had sex on cam a few times ... but I guess that is not the same as someone being present in person.