When I use a mocking bird

Of all types of slang, perhaps the best known is Cockney rhyming slang. It developed in London during the first half of the 19th century, at about the same time as Robert Peel was inaugurating his police force, perhaps to be used by criminals as a secret language that the slops (back slang, from ecilop) would not understand. Later, it spread with the convicts who were deported to Australia, and then to America, where it became known …