A phrase often used by people who work in Customer service, which describes a person who goes into shops or phones up companies with the sole purpose of starting an argument or causing trouble.
For example, they might go into a shop and ask for a product, knowing full well the shop doesn't stock it, and then kick up a fuss when they're told "Sorry, we don't stock that".
Another example would be deliberately misinterpreting what the sales advisor says or taking it out of context, then complaining to the manager about rude staff and bad customer service.
I used to work in the Customer Services department of a mail order company. A woman phoned me to slag off anything and everything about the company, and then started with the personal insults directed at me. After all this, she was still pretty taken aback when I dared to disagree with her. Personally I don't care if you're the customer, I still think you're wrong you bitch! She accused us of being misleading, when she was clearly a very intelligent woman and could understand our catalogue perfectly. She just had too much time on her hands.
Several minutes later she faxed over a letter of complaint, accusing me of saying and doing things which I never said or did. Looking at the length of the letter, she would've had to type about 160wpm, which is pretty impossible. The only other explanation was that she'd prepared the letter beforehand. Of course, my boss from hell was one of those "the customer is always right" people, and believed the customer over me. I quit my job. The only good thing about the whole incident was that I got myself a new and much better job!
I threw the letter away, but I kept the woman's name and address, incase I ever think of an evil way of getting my own back.
So there you have it: stupid customers are not so bad as long as they remain polite. It's the clever ones you should watch out for.