whistle and flute

"Whistle and flute" is a phrase used in Cockney rhyming slang to refer to a suit, specifically a formal or business suit. The phrase originated in the late 19th century in the East End of London, where Cockney slang was commonly spoken. In this distinctive form of slang, words or phrases are substituted with rhyming words or expressions. In this case, "whistle and flute" rhymes with "suit," so Cockney speakers would use the phrase "whistle and flute" to mean a suit.