The other day in a bookshop I found a dictionary of London taxi driver slang. It's a little dictionary and only cost £2.50 but, if you're a Londoner, it's rather fun. (If you're not a Londoner, I fear this post may be dull.)
It's the place names that are pleasant. The Stock Exchange is, apparently, known as Thieves' Kitchen. The twelve back streets that run through Soho from Regent Street to Charing Cross Road are the Dirty Dozen, and Covent Garden is still known as the Flower Pot, despite the fact that there hasn't been a flower market there since 1974.
But my favourite definition was:
Dead Zoo - Natural History Museum
The Pancake, apparently.
(The bar at the nearest corner is the most beautiful in London)