Story 1:
After leaving school and gaining some local acknowledgment our school invited us back to play at a full school assembly in front of the whole school (roughly 1600 students). Anyway we're a laid back sort of beach band (most of our songs where written in the back of a station wagon with the boot open facing the ocean) so we obviously look the part on stage. Shorts, singlets and no shoes. So I'm bopping along to the second of four songs we are to be playing and turn around to face the drummer. Suddenly I get a sharp pain in my foot, I look down to see that for some strange reason there was glass on the stage (which was indoors) and I had cut my foot open from toe to heal (almost). I continued on leaving foot shaped stains on the carpet before the song stopped for some reason. I looked over at the rest of the band who were just staring at me, then I realized that I had completely dazed out and was standing motionless, pale and not playing. Had to go to hospital for stitches.

Bad gig.
Story 2:
My first ever band was playing at battle of the bands in front of my school. Anyway, we get up for our sound check which is being run by the school theater tech. Now, let me tell you about the school theater tech, he is a 40+ guy who blows his fuse at the drop of the hat and scares all the students into submission, I was one of the only kids who ever just laughed off his threats and yells. So I do my bass and vocal sound check and turn around to start tuning my bass. I get about half way through when I hear yelling from the sound desk, I turn around to see the theater tech walking towards the stage, red faced and looking angry. Anyway, he gets to the stage and yelling at me for not paying attention and I calmly inform him that I did not hear him address me as I was tuning up my bass. Anyway he has his little tantrum and informs me that we where doing a full band sound check, I do the sound check, he gives the thumbs up from the sound desk and I go back to tuning (we weren't on for another 20 minutes).
Here comes the fun part, I just finish tuning up when I feel a hand grab my arm and violently pull me around, it was the theater tech who obviously had tried to get my attention (silently) whilst I wasn't looking and blown another fuse. Anyway, in the act of spinning me around my strap detaches itself from the bass and I cant catch it because he has my arm in his vice grim. The bass falls the the floor, headstock first and I watch as the headstock snaps in twain, completely ruining the only bass I could afford at the time (I was 16).
Ok, so I'm normally a calm person but all those years of him yelling at me and everything else just accumulated into one reservoir of rage, the dam of which burst with the breaking of my bass.
I went mental. I pushed him away from me, causing him to almost fall off stage and I took my now useless bass and threw it solidly at one of the P.A. speakers (both of which he owned) which it struck sweetly, sending it toppling off the stage and onto the ground, breaking it instantly. I stormed off stage and walked out the door, flipping the bird and calling him some unpleasant names along the way.
I was nearly expelled and he was fired for the both the incident and the numerous complaints that had been filed against him throughout his years at the school.
Funny addition: A few months ago I was to play a gig in the city (I'm 18 now, so older and out of school obviously) only to find HE was the sound guy there. He demanded to speak to the manager and refused to do sound for us. I simply retorted, "That's ok we brought our own sound guy". Which we had.
Oh the memories.