From The Telegraph:
Eleven years ago, I read books for Jonathon Green, who I’d heard was researching a slang dictionary. A fun-sounding project turned out to be the compilation of an enormous computer database, with citations for printed usage, over the last 500 years – the most complete record of its kind. This voracious abstraction, to which I fed titbits for a couple of years, is now about to be published in three large, and appropriately green, hardback volumes. Training began with a pile of early PG Wodehouse novels. These related the adventures of Psmith, the man about town who revelled in such phrases as “last night’s rannygazoo” several years before Bertie Wooster began to bounce them off the silver-plated English of Jeeves.
Rannygazoo (“nonsense; irrelevant, irritating activity”) was an easy spot. And because Wodehouse is full of such exuberance, marking up the books seemed a breeze. I remember my disappointment when I learnt that I was regularly missing useful citations. When you begin to study it, much more familiar language reveals itself as slang. A few pages on in the new dictionary, for example, Wodehouse yields a citation for the “coarse, dismissive, jeering noise” that most people would call a “raspberry”. As the definition indicates, it doesn’t have another name – I had always dimly thought of it as a more fruity sort of “rasp”. But it actually derives from rhyming slang, where phrases are often shortened to exclude the rhyme that reveals the word intended – and, in this case, the thing imitated (“raspberry tart”).