We've had two:
1) The "doing it in a parked car" scenario. A cop comes up to the car and we're completely naked. Mrs. Nova (we were just dating at the time) is saying "don't tell him my name don't tell him my name don't tell him my name"
See, at the time her daddy was a senior highway patrolman...
2) Again, still while we were dating - doing it doggy style in the guest room at my parents' house when there's a knock on the door... Luckily we'd locked it, but I still got a lecture.
Nova