You Owe Us $0.00
A guy got a credit card bill stating that he owed $0.00. He ignored it and threw it away.
Next month he got another, did the same thing. The next month they sent him a very nasty note stating they were going to cancel his credit card if he didn't send them $0.00.
He called them, talked to them, they said it was "a glitch" and told him they'd take care of it.
The following month he tried to charge something and couldn't. He called the credit card company who again said they'd take care of it. The next day he got his bill for $0.00 stating that he was very delinquent.
The man figured the credit card company would take care of it, so he didn't worry. The next month he got a bill for $0.00 stating that he had 10 day to pay or his account was going to collection.
He mailed the credit card company a check for $0.00, and the credit card company's computer processed it, noting that his account was now paid in full.
A week later, the man's bank called him asking him what he was doing writing a check for $0.00. He explained and they said, "Well, your $0.00 check has caused our check processing software to fail. We now can't process ANY of our checks from that day electronically because that $0.00 check is causing the program to abort."