One of the funniest "most-embarrassing-moment" stories I've come upon in a
long time was about a lady who picked up several items at a discount store.
When she finally got up to the checker, she learned that one of her items 
had no price tag. Imagine her embarrassment when the checker got on the 
intercom and boomed out for all the store to hear, "PRICE CHECK ON 
LANETHIRTEEN, TAMPAX, SUPER SIZE." That was bad enough, but somebody at 
the rear of the store apparently misunderstood the word Tampax" for 
"THUMBTACKS." In a businesslike tone, a voice boomed back over the 
intercom. "DO YOU WANT THE KIND YOU PUSH IN WITH YOUR THUMBOR THE KIND
YOU POUND IN WITH A HAMMER?"