If they feel stupid, then I have won...

*phone rings*
ME: *speaking mechanically* Hi, you've reached the helpdesk, may I have your user ID please?
CALLER: My what? I'm sorry, I can't hear you.
ME: *slowly* Hi, we're the computer helpdesk. Could I have your user name for logging on to the computer?
CALLER: Oh, I don't have a computer. I'm not calling about a computer. I'm calling about coupons. I must have the wrong number
ME: Okay, if you are calling about one of our company's products, I can give you the phone number for our company's product.
CALLER: No, I'm not calling about one of your products. I'm calling about coupons. I must have hit the wrong number
ME: Okay, if you're calling about coupons for one of our company's products, I can give you the phone number for our company's products.
CALLER: I'm not calling about a product! I'm callin about coupons! I'll just call back.
ME: Are you calling about coupons for one of our products?
CALLER: Yes.
ME: Okay, if you have questions about coupons which are for one of our products, then they would answer that at the product support line. I can give you that phone number.
CALLER: Oh... uh, sure...