Green’s Dictionary of Slang

1. (UK Und.) alcohol; thus rare-lapper, a hard drinker [lap n.² (2)].

1873		Sl. Dict. 212: Lap a ‘rare lapper,’ a hard drinker.
1888		H. King Savage London 37: I was a rare lapper in them days, and you were a reg’lar wooled un to stand up to me then.
1890–1904		Farmer & Henley Sl. and Its Analogues IV 155/2: subs. (thieves’). 1. Drink [...] Hence, rare-lapper = a hard drinker.
1920		Western Argus (Kalgoorlie, WA) 15 June 1/4: An inveterate imbiber is called ‘a steady lapper’.

2. (US) the tongue; thus cool one’s lapper v., to have a drink [SE lap].

1851

M. Reid Scalp-Hunters II 44: At thet very spring the Injuns ’ll cool thur lappers.

3. (Ling. Fr./Polari) a hand.

1991		(ref. to 1930s) in Porter & Weeks Between the Acts 138: Hands are lappers, legs are lallipegs, breasts are jubes.
2019		P. Baker Fabulosa 294/1: lappers hands.
2023		R. Milward Man-Eating Typewriter 19: Novak’s hardback liver clenched in his right lapper.

4. one who performs oral sex [see lap v. (4); def. in cite 1949 presumably inaccurate].

1934		‘J.M. Hall’ Anecdota Americana 181: Synonyms for male homosexuality [...] Fairy, pansy, queen, floosie, cock-socker, gobbler, queerie, dickie-licker, femmie, Nancy, fruit, lapper.
1949		Monteleone Criminal Sl. (rev. edn) 141: lapper A sodomite.
1968		F. Exley Fan’s Notes 262: Mr. Blue [...] had some deranged notion of the typical housewife [. . .] yearning for oral stimulation of her labia. [. . . .] Mr. Blue smiled knowingly, letting me know that [. . .] ‘broads can spot lappers’ and doors would open for me like so.
1972		B. Rodgers Queens’ Vernacular.
1997		Roger’s Profanisaurus in Viz 87 Dec. n.p.: lapper n. A musician who plays the pink oboe (qv) a hairy pie eater (qv).