For some reason, I've ended up working during the same concerts I attend. (Reinforced by the fact that, of the two I wasn't working for, The Dissociatives one got cancelled because Daniel Johns got a sore throat, and I was too late to get into the One Night Stand.)
As such, my concert horror stories put me in the antagonist's position.
The first was the Tamworth Country Music 2004, at a bar. Warm weather and a fridge door left open had made the alcohol warm, and I copped the brunt of the blame for it, despite me not being the cause. It wasn't helped by me not really doing anything to rectify it, so yeah, things went to hell, and I ended up losing my job because of it. It was my first one, too, so yeah, great start to my working life!
The second was a "prequel concert" to the aforementioned One Night Stand, called First Kiss. I was on the organising committee for the concert, and was assigned to the door on the night. We had security there, but at one point they had to do a circuit of the concert grounds (an old gaol), leaving me at the door. Now, I have no security training whatsoever, so procedure for bag checks...yeah, I was a bit too intrusive. In my head, I was, "Can't let drugs through," but that very much came out in what I did, as I was searching for it, when proper procedure was just a cursory glance.