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

[Travelling Man]

Since we are all "invisible"--and presumably un-traceable--please share with the forum what you feel was the worst blunder, missed call, error, or mishap you've made while working a game.

I'll go first, I inadvertently called a throw-in violation based on a 3-second call instead of a 5-second call and this caused a loss of possession by the eventual winning team.

I missed a call on a "jump ball" situtaion when the defender blocked the shot while shooter still had ball--you know the simultaneous "shot attempt - blocked shot"--I mistakenly called travelling. uggghhh so mad at myself--grrr!

But, I must say I've learned from all of these blunders.