Green’s Dictionary of Slang

fifi n.

[? Fifi, the clichéd name of the stereotyped sexy French maid of farce and fantasy; note Hotten (1864–70): ‘Fi-Fi, Mr Thackeray’s term for Paul de Kock’s novels, and similar modern French literature’]

1. (also fiff) an effeminate or ‘aesthetic’ man.

[US]‘Hugh McHugh’ John Henry 57: Well, there’s no literary fiff that can give me the elbow.
[US]D. Jenkins Rude Behavior 6: ‘I suppose shirt-lifter is better than fag,’ I said casually. ‘Sounds almost jovial.’ ‘Shirt-lifters . . . greyhounds . . . Fifis . . .’ .
[SA]K. Cage Gayle 70/1: Fifi n. effeminate gay man.

2. (US gay) one who enjoys oral sex.

[US]B. Rodgers Queens’ Vernacular 80: fifi (’40s, fr pros sl = one who enjoys being blown) 1. anybody who derives pleasure from mutual fellatio or cunnilingus.

3. a French prostitute working in London.

[UK] (ref. to WWII) Indep. Rev. 11 Nov. 6: During the Second World War [...] ‘Fifis’ – the professional Frenchwomen who then made up most of London’s streetwalkers.
[UK] (ref. to 1940s–50s) K. Waterhouse Soho 11: The war years and beyond, when [...] the girls, or Fifis as they were known, were as thick on the pavements as the pigeons in Trafalgar Square.

4. (US campus) an attractive, sexy young woman, who dresses to match but is, in the end, considered superficial.

[US]P. Kendall Dict. Service Sl. n.p.: Fifi . . . the current girl friend. Sometimes it might be her name.
[US]P. Munro Sl. U.

In compounds

fifi bag (n.) (also fifi) [sense 1 above]

(US prison) a substitute ‘vagina’ for masturbation; one version uses a container stuffed with a towel soaked in warm water; for another see cit. 1990.

[US]B. Rodgers Queens’ Vernacular 79: fifi-bag (kwn LV, late ’60s, fr Fr sl girl’s name Fifi = a tart) homemade masturbation utensil made with hot towels and vaseline or a well-lubricated slit sponge tucked into a baggie.
[US]Maledicta V:1+2 (Summer + Winter) 265: Males, bereft of female comfort, sometimes resort to a fi-fi bag, a plastic sack containing a warm, wet towel used as a vagina.
[US]S. Morgan Homeboy 211: Fifi bag’s a phony snatch. They take orange juice cartons [...] cut em in half and stuff em with a baggie loaded with hand lotion.
[US]Bentley & Corbett Prison Sl. 63: Fifi Bag Some type of bag or container which is filled with a lubricant and used to masturbate.
[US]Other Side of the Wall: Prisoner’s Dict. July 🌐 Fifi Bag: An artificial vagina used for masturbation.
fifi water (n.) [sense 1 above, the presumed effeminacy of those who use it]

(US prison) aftershave.

[US]S. Morgan Homeboy 299: The whiteboys splashed on fifi water and groomed their mustaches.