Unexpected cause-effect :)

A famous art collector, walking through the city, noticed a mangy cat lapping milk from a saucer in a store doorway, and recognized the saucer as Ming pottery, extremely old and very valuable. He walked casually into the store and offered to buy the cat for two dollars.
The storeowner replied, "I'm sorry, but the cat isn't for sale."
The collector said, "Please, I need a hungry cat around the house to catch mice. I'll pay you twenty dollars for that cat."
The owner said, "Sold," and handed over the cat.
The collector paused, "Hey, for the twenty bucks I wonder if you could throw in that old saucer. The cat's obviously used to it and it'll save me from having to get a dish."
The owner said, "Sorry buddy, but that's my lucky saucer. So far this week I've sold sixty-eight cats."