It's funny working retail, you see people you probably wouldn't encounter in the rest of your life. I think of the oddest people as Zombie Customers, or maybe Customers from Another World. Their understanding of the entire employee/customer relationship is completely foreign to the rest of the world.
The one I'm thinking of at the moment is the customer that doesn't take "no" for an answer when they're looking for a product. Even when you give a little lecture as to why the product isn't there, they just look on, uncomprehendingly, until you resort to extreme measures. The next line of their programming only accepts the input "ah, here it is", then the customer executes Purchase_Item.exe