Green’s Dictionary of Slang

1. a coal-heaver’s fantail hat.

1819

P. Egan Key to the Picture of the Fancy going to a Fight 16: These Black diamonds [...] are larking each other’s flappers, and have each of them just tossed off a drop of max .

2. the hand.

1834		Marryat Peter Simple (1911) 215: My dear Mr. Simple, extend your flapper to me, for I’m delighted to see you.
1845		Bell’s Life in Sydney 13 Dec. 2/2: Hough [...] succeeded by a round sweep with the dexter flapper, catching Haddy under the left ear.
1859		Matsell Vocabulum 32: Flappers Hands.
1864		Dublin Eve. Mail 21 July 1/6: Her suddenly thrusts his ‘flapper’ at you [and] you feel your hand enveloped as in a fleshy vice.
1866		London Misc. 19 May 235: Theres my flapper on the strength of it. Guy shook hands with the eccentric stranger heartily [F&H].
1873		Sl. Dict.
1889		Whitstable Times 23 Feb. 7/6: The man tried to pullhim along by putting a hhooked stick in his large ‘flapper’.
1895		Crowe Aus. Sl. Dict. 29: Flappers or Flippers, hands.
1906		Sun. Times (Perth) 1 July 4/7: Put your flapper in your kick.
1907		W.M. Raine Wyoming (1908) 81: I reckon Cousin Ned’s my meat. Y’u see I get him in the flapper without spoiling him completely.
1909		J. Ware Passing Eng. of the Victorian Era 133/1: Flapper (Lower Class). Hand sometimes flipper.
1913		Day Book (Chicago) 21 Feb. 12/1: Throwing the spitball [...] seems to have affected the right flapper of Ford [...] one of the American League sensations.

3. the (flaccid) penis.

1890–1904		Farmer & Henley Sl. and Its Analogues.
1980		Maledicta IV:2 (Winter) 195: The flaccid part is referred to as Hanging Johnny, doodle-flap and flapper.

4. in pl., the labia majora.

1888–94

‘Walter’ My Secret Life (1966) IV 787: She had huge flappers to her cunt, — an ugly sight.

5. (Aus./US black) the mouth or tongue; thus in pl. the lips.

1900		Bendigo Indep. 27 Jan. 2/3: If vou take my tip you’ll shut your mouth, and keep that flapper of yours from wobbling too much about who the real person was as knocked over the keeper.
1944		D. Burley Orig. Hbk of Harlem Jive 17: The banter laid her stealers on her flappers, and booted her to the jive that the skull was trying to drop a hype on her.
1983		R. Klein Jailhouse Jargon and Street Sl. [unpub. ms.].

6. (US) in pl., the ears.

1907		Sun. Times (Perth) 17 Feb. 4/8: When you know from the Fields to the Coast / On his auricle flapper they swung.
1934		Weseen Dict. Amer. Sl. 334: [General] Flappers – The ears.
1935		Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks 4: Flappers: Ears.
1975		L. Dills CB Slanguage.

7. (UK tramp) in pl., the boards carried by a ‘sandwich-man’.

1932

F. Jennings Tramping with Tramps 163: The boards which the sandwich-man carries round used to be called his clappers. Someone substituted ‘flappers’ for this.

8. in pl., exaggeratedly long, pointed shoes.

1937–84

Partridge DSUE (1984) 401/2: from ca. 1880; ob.

9. in pl., the arms.

1944		‘Jiver’s Bible’ in D. Burley Orig. Hbk of Harlem Jive.
1971		(con. 1930s–50s) D. Wells Night People 117: Flappers. Arms.

10. an impotent old man.

1980

Maledicta IV:2 (Winter) 190: Flap-doodle, doodle-flap, flapper and floater may refer to a young boy or to an old man, the one never having exprienced a cock-stand and the other a matter of memory.