To talk.
A cant used in the London fishmarkets, in the British theatre, and by the homosexual community in Britain, attested since at least the 19th century and popularised in the 1950s and 1960s by the camp characters Julian and Sandy in the popular BBC radio show Round the Horne.
The word comes from Italian parlare, meaning "to talk," but its spelling reflects how a non-rhotic British accent altered the original sounds. It likely entered English around 1846 as part of a Romance-based pidgin or creole used by performers.