The Worst Error You've ever made reffing a game?

[Welpe]

My worst was not calling a flagrant foul on a play where a defender deliberately clotheslined the ball handler on a full sprint towards his basket. My partner talked me into going intentional and I let him. Looking back on it, there's no way it wasn't flagrant.

My runner up was giving the inbounding team the ball on their end line instead of on the opponent's where it should have been. I was working by myself and we had just come out of a timeout and I got turned around. Whoops.