quality story.
My first time was with the mom in the house, but we were quite quiet so it was no biggie. However I had my first run in with someone walking in on sex just last friday night. I was at a party with this girl I had already fucked a few times, and we all got pretty damn slammed, there was about 8 people or so crashing at the house with her whole family there as well (in Germany so parents chill about drinking), so I end up sleeping on the couch with her and while everyone is doing that awkward small talk before going to bed, we're already rounding towards 3rd under the sheets and I just say "bathroom" since no one is there, she nods, I grab a condom, head to the bathroom. After about 10-15 minutes or so the sister knocks on the door wanting to go to the bathroom, she says wait, but comes in as im hiding behind the door, I then proceed to walk out, giving her a nice smile with a raging boner under my boxers.
And no, I did not ask her to join.
Go back in 5 minutes later finish the deed, then go back to sleep with the rest of the party acknowledging what we had did.
Solid night indeed.