A district of Ankh-Morpork known eponymously as a kind of rhyming slang... somebody with a poetic education must have reasoned that the drawback with most rhyming slangs is that it isn't terribly hard to reason back from the slang word, to the relatively few things that rhyme with it, in order to deduce a meaning. As a secret language or a thieves' cant, it kind of loses out on the secrecy thing. Therefore, just as blank verse and arrhythmic lines are a sophisticated step on from poetry that scans and rhymes, Dimwell Arrhythmic Rhyming Slang was born, where "plates of meat" might mean "kippers".
Dimwell is the downtown area of Ankh, across the river from The Shades and including similar (but more reputable) dock and industrial areas, but also Hide Park. The district is bisected by Dimwell Street between Hide Park and the Traitors Gate. Other locations include Mollymog Street and the Gibbet.