lean, v.¹ — Green’s Dictionary of Slang

lean v.¹

[the image is supposedly that of a pimp cruising the streets with his whores]

(US black/west coast) to drive a car while leaning out of the window.

1970		Current Sl. V:2 9: Lean, v. To drive a car while slouched over toward the left window.
1980		E. Folb Runnin’ Down Some Lines 114: Essentially to lean means to lean inwards from the window, as if you are resting your arm on a console or armrest [...] while steering the car with your left hand (or as a passenger, with your left hand braced against your leg or waist as you lean inward).

lean against the engine (v.) [the recumbent posture of opium smokers, and the concomitant smoke]

(US drugs) to smoke opium.

1942		Berrey & Van den Bark Amer. Thes. Sl.
1953		Anslinger & Tompkins Traffic In Narcotics 312: lean against the engine. To smoke opium.

lean-away (n.)

(Aus.) a drunkard.

1937–84		Partridge DSUE (1984) 671: ca. 1890–1910.
1955		N. Pulliam I Travelled a Lonely Land (1957) 235/2: leanaway – a drunk person.

lean over backwards (v.)

lean-to (n.)

a lodging house, night shelter or similar refuge for homeless people.

1941

V. Davis Phenomena in Crime 255: The lean-to. A doss-house.

on a lean (adj.)

(Aus.) waiting, lit. leaning (e.g. on a wall).

1912

Bulletin (Sydney) 26 Sept. 15/1: ’T’ keep a lydy on a lean / Where passin’ cobbers grin ’n’ yap / Is dead low down.