A few years ago I called one of our local offices for some reason, and as soon as they picked up the phone I heard a UPS beeping in the background. Conversation went as follows:
Me: Why is the UPS beeping like that?
Them: Isn't it supposed to beep like that all the time?
Me: (sarcastically) Yes, that's the "everything's OK" alarm. It'll beep like that if everything is ok.
Turned out they'd unplugged the computer so they could plug in an electric pencil sharpener... Oh dear...