An antique collector pays a visit to his local curiosity shop, looking for something just that little more unusual than tatty lamps and scabby old furniture.
After asking the dealer if he had anything unusual, the dealer produces a brass rat, he then starts to tell the story of how it came to be and the problems it had brought. The collector was in a bit of a rush so cut the dealer short and took the rat without listening to the story.
After jumping on his bike and starting to peddle home, he hears a faint scurrying sound, turning round he sees a couple of rats struggling to keep pace with him. Thinking it strange but not disturbing he continues on. A little furthur along he hears what is now a rather distinct clattering of chitinous claws behind him, turning he sees hundreds of rats and more pouring out of drains and buildings.
Peddling hard and just a little worried he reaches a bridge and stops to see what is happening behind him. Thousands of rats are running towards him in a black wave.

Deciding it must be to do with the Brass Rat in his bag he hurls it over the side of the bridge into the water, only to see thousands of rats pile off the edge into the river and drown.
A little flustered he goes back to the antique shop.

"Aha! says the dealer, NOW you want to hear the story"

"Not really says the collector, I'm just wondering if you stock brass scousers"

:D