Clical Music Concert Bloopers...what's the funniest one you've ever experienced?

At a chamber music camp concert, the final and best quartet was performing. (The most advanced high school quartet). I was helping with stage changes and stuff, so I was backstage. The way the stage and house were built, you couldn't leave backstage without the audience seeing you. (Bad design . . . ) So there was a kid that was trying to leave during this quartet performance. I told her to wait the 5 minutes for them to finish so she wouldn't be distracting. So she leaned back against the wall, and against the light switch board thing. And brought ALL of the lights down. Backstage, stage, house, EVERYTHING. The other guy backstage with me was the orchestra teacher there and knew where the switch was, came running, turned the lights back on, and the quartet just kept on playing. To listen to the recording, you wouldn't know anything had happened.