Caller is running a PAYPAL scam. Wants to buy something you have posted on the internet, then pays you extra through PAYPAL, and either:
1. asks you to send the overage back using a bank draft or money order. Then you will find out that the paypal transfer was fake, and your bank draft was real, so you're out the whole amount, or
2. tells you the paypal transfer won't go through until you ship the item. Once you do so, you learn that the paypal transfer was fake, and you're out your item. This scenario is usually something very expensive, ie: a car, jewelry, antique furniture, etc.