ugh. i am in high school. most of the time there is something going wrong.
our theatre club puts on a talent show every year and since we didn't have our own comm system at the time, we had to rent one for anything we did.
well, our director forgot to rent them for the talent show, so we had walky-talkies. ugh. it was terrible.
when we aren't doing theatrical performance, i usually run the light board. during a band concert at my school (i'm in band, so it's the only kind of performance at the school where i can't be behind the light board), someone was leaning on our amp stand which has backstage controls for the lights that override the board.
in the middle of our song, the lights go out. i sit there for a second, knowing exactly what the problem was, deciding whether to get up or not. after a few seconds i got out of my chair and turned the lights back on. my first standing ovation!
another time, a local elementary school was performing in our theatre and needed some of my school's students to do tech. i wasn't able to attend because of SAT's (ugh) so my director had some actors do it. i came in later in the day to discover the light board was in something called "park mode" and i couldnt turn off any of the lights on the stage. turns out, they didnt turn on the monitor and were just pushing random buttons.

long story short, don't let high schoolers who happen to be actors around your technical equipment.