For me, it was when i was still in high school (along long long time ago) my girlfriends mom had just left the house so my girlfriend placed a blanket down in the family room cranked up the stereo we got completely naked and started going at it. She was on top riding me and all of a sudden she jumped off me and hid behind the sofa. There I was sporting wood in the middle of the room while her mother is staring straight at me. I flipped to my stomach and grabbed the blanket, but the damage was done. She kept yelling at my girlfriend for what seemed forever. Needless to say every time I saw her mom it was very awkward.