I confess that I had my first orgasm while watching my twin sister being spanked by our dad.
She had wet the bed, and he was spanking her over his lap very hard. I was in my own bed, with my eyes peeking out from the covers, pretending not to be watching. She was crying a lot, and struggling, and her left leg kept slipping off his lap, revealing her privates. I was stroking myself gently under the covers.
Finally she started begging "please daddy! Stop! I'll never do it again! Please!"
I don't know if it was the fear or shame in her voice, but something about her desperation just made me lose it.
I felt so guilty afterwards. I couldn't look her in the eye.
