This is not a new joke, but I revised it to make more sense than the original...----------
A tourist walks into a curio shop in San Francisco. Looking around at the exotica, he notices a very lifelike life-sized bronze statue of a rat. It has no price tag, but is so striking he decides he must have it. He takes it to the owner:
"How much for the bronze rat?"
"$12 for the rat, $100 for the story," says the owner.
The tourist gives the man $12. "I'll just take the rat, you can keep the story."
As he walks down the street carrying his bronze rat, he notices that a few real rats have crawled out of the alleys and sewers and begun following him down the street. This is disconcerting, and he begins walking faster. But within a couple of blocks, the herd of rats behind him has grown to hundreds, and they begin squealing.
He begins to trot toward the Bay, looking around to see that the rats now number in the MILLIONS, and are squealing and coming toward him faster and faster. Concerned, even scared, he runs to the edge of the Bay, and throws the bronze rat as far out into the water as he can.
Amazingly, the millions of rats all jump into the Bay after it, and are all drowned. The man walks back to the curio shop.
"Ah ha," says the owner, "you have come back for the story?"
"No," says the man, "I came back to see if you have a bronze Democrat."