Green’s Dictionary of Slang

Dorothy’s friend n.

a homosexual.

1972		B. Rodgers Queens’ Vernacular 66: Dorothy (rare) vocative used before a lecture, comparable to the ‘Buster’ of an irritated New York cab driver. Dorothy and Toto 1. gay boy and his dog 2. dominating effeminate homosexual man with his paid-for escort 3. extended to any male couple whose effeminate partner is in command.
1995		A. Heckerling Clueless [film script] Yo, look. Are you bitches blind or something? Your man, Christian is a cake-boy! [...] He’s a disco-dancing, Oscar Wilde-reading, Streisand ticket-holding friend of Dorothy, know what I’m saying?
2000		Indep. Rev. 24 Jan. 8: When your airline is a friend of Dorothy’s [...] The travel business now realises that gay customers are a profitable niche in the market.
2004		Guardian Weekend 7 Aug. 31/1: Those were the days when gay punters had to ‘knock twice and ask for Dorothy’.
2011		Eve. Standard 14/3: Bachmann, a ranting homophobe [...] is widely rumoured on the Internet to be himself, something of a ‘friend of Dorothy’.
2013		slate.com 19 June 🌐 Revealing men’s swim garments are, for the U.S. consumer, irrevocably associated with ‘foreigners’ and, most terrifying of all, friends of Dorothy.
2016		Twitter 17 May 🌐 So one of the furniture delivery gentlemen admired our portrait of Judy Garland. Wonder if he’s a friend of hers, so to speak.