Ed Simon at The Millions:
A direct line runs between the vibrant, colorful, and earthy diction of canting to cockney rhyming slang, or the endangered dialect of Polari used for decades by gay men in Great Britain, who lived under the constant threat of state punishment. All of these tongues are “obscene,” but that’s a function of their oppositional status to received language. Nothing is “dirty” about them; they are, rather, rebellions against “proper” speech, “dignified” language, “correct” talking, and they challenge that codified violence implied by the mere existence of the King’s Speech. Their differing purposes, and respective class connotations and authenticity, are illustrated by a joke wherein a hobo asks a nattily dressed businessman for some change. “’Neither a borrower nor a lender be’—that’s William Shakespeare,” says the businessman. “’Fuck you’—that’s David Mamet,” responds the panhandler. A bit of a disservice to the Bard, however, who along with Dekker and Middleton could cant with the best of them. For example, within the folio one will find “bawling, blasphemous, incharitible dog,” “paper fac’d villain,” and “embossed carbuncle,” among such other similarly colorful examples.
more here.