I've knocked out my wife (at the time gf) once, with a right upper cut straight to the jaw.

I had a boxing fight in a couple of days, coming up. I went to sleep early, while she went out with friends.

When she arrived back, she climbed on top of the bed. I woke up and felt was a presence on top of me, so I threw a punch from my back, and knocked her clean out. She fell in between the apartment wall and the bed.

Fun times 😂