It was at a party called First Contact. We had rented a really nice light rig that consisted not only of your standard track spots and floods, but a nice rectangular arch that had 5 huge strobes mounted on it. These strobes were massive, and had a relatively long cycle time once fully discharged until they could be used again. The controller had several fun settings, sequential, all at once, slow fade, etc. We were pretty excited about it, and I had a lot of fun playing with it during sound check and later on during the actual event.
Until all the the lights went out. Along with both sound systems to both rooms. In the middle of the party.
There was much cursing, and flashlights came out as the breaker box was located and reset. Tunes once again filled the main room, and so did light - at least until the next time someone triggered all 5 strobes at once.
Plunged into darkness a second time, then a third time, then a fourth, our exasperated techs explained for the AGAIN why it was impossible for the rig to be overloading the building's wiring like it was. Frustrated that we couldn't exploit our impressive lighting to it's maximum, we had to abandon the use of the strobes completely.
An hour later, our light tech was on a break and strolling around the venue when he caught the distinctive odour of fresh-brewed coffee. Intrigued, he followed his nose all the way to the coat check cloister, where he stood and stared in disbelief. Right underneath a large sign that read, in capital letters "DO NOT USE THIS OUTLET" (posted by said tech), was a coffee maker. A 15 amp coffee maker. Plugged into a 15 amp circuit that just happened to be used by the light and sound rig.
Never make the assumption that coat check girls can read.
In fact, just don't throw a rave.