My first IT job was in a large call center. I was sweeping up in a data center and there was a keyboard cable stretched across a walkway. The keyboard wasn't movable (I don't remember why) so I unplugged it from the PC, swept around it, and plugged it back in. About 2 minutes later half a dozen people run into the room. Apparently the SUN workstation I had unplugged the keyboard from was a critical component of the call manager and there was a bug that forced a reboot when the keyboard was plugged in while the system was running. I had hung up on ~36,000 people. Lesson learned and I only had to keep the data center clean for another year.