"Why is the UPS beeping?"
"I don't know; it must be busted."
"Hope we don't have a power outage."
<later>
"Now it's beeping much louder and more frequently."
"That thing probably hasn't worked in years."
"I'll order a new one."
<ten seconds later, computer shuts down>
"Hey look, the UPS wasn't plugged in."
"Aww...it was trying as hard as it could to warn us, and we just assumed it was broken and didn't listen, when in reality it was just faithfully doing its job."
