Muffins the Psychodemon

Muffins the Psycho Demon is a two faced customer that starts out friendly and pleasant, but turns into a raging psycho bitch or crazed bastard when they don't get what they want.

Example:
 * A grandfatherly old guy calls in, speaking in glowing terms about the excellence of your customer service. He then asks for a refund.  Policy states that you cannot issue a refund.  Suddenly he starts in on a barrage of verbal abuse, accompanied with generous amounts of profanity.  When you make an exception and give the old bastard his refund, he reverts to his previous form, apologizing profusely and saying what a saint you are for putting up with him.  Just think of what would happen if you took it all back, canceled the refund, and said he wasn't getting shit.
 * A woman calls you, patiently goes through the verification process, then politely requests a 100% refund on her order, plus the amount of the premium member coupon the company issued. When you tell her she can't get the coupon and/or more than 50% of the refund, her volume increases, she uses more blue words than a sailor, and she demands a supervisor, and possibly your head.  When she finally gets the refund, she calms down and apologizes for being a psycho bitch.