What's the biggest f'up you or someone at work has made?

A former manager of mine. He was head of security for a shopping centre. I had been reminding him that for weeks, the Christmas lights switch was rapidly approaching, and he needed to make plans for the car park to stay open later than usual, instead of closing at 6.30pm. He kept fobbing me off, saying it won't be a problem. The day comes and it so happens I'm working in the car park office that day. 6.30pm comes around and there's approx 250 cars left in the car park. As he hasn't put anything in place, I finish my shift, lock up, and go home. Sure enough, a short while after 9pm, hundreds of people come back to the shopping centre to find it all locked up. They managed to contact the night security guard... who was a nasty, short tempered, vile old man who pretty much hates everyone. Instead of doing the right thing and calling someone, he just flat out refuses to do anything at all. They phone the police and the police arrive and still the night guard won't budge. Only when the 2nd night guard comes back from a beat check does anything happen. 2nd guard calls management and gets the go-ahead to open up the car park. Management tells him to not only open it up but to put the exit barriers on permanent open and let everyone out for free. The next problem is, they're exclusively the night shift. They aren't trained on operating the car park computers or know how to manually open the barriers. They don't even know which keys unlock the car park shutter. It just so happened. There was a reporter from the local paper with the angry crowd, and he ran a scathing piece on the whole dilemma. Shopping Centre management are beyond furious. Obviously, someone has to take the shit for it. So the buck stops with nasty, short tempered, vile old man night guard. He was given a written warning and disciplinary action taken against him.