Green’s Dictionary of Slang

slick adj.

1. [mid-19C+] (US, mainly teen) a general term of approval, clever, sharp; thus slickness n.

2. [1970s] (US campus) attractive (of either gender).

In compounds

slick-ass (adj.) [-ass sfx]

[1970s] smooth, sophisticated, smart.

slick-boy (n.)

[1990s+] (US black) a confidence trickster, a cheat, a liar.

slick chick (n.) [chick n.1 (3)]

[1930s+] (US black) a smart, attractive young woman.

slick citizen (n.) [citizen n. (2)]

[1900s–10s] (US) an unprincipled individual.

slickdick (adj.) [generic use of proper name]

[1990s+] cunning, self-promoting, ‘smooth’.

slick duck (n.) (also slick coot) [duck n.1 (4)]

[1900s–10s] (US) a cunning, sly person.

slick-leg (adj.)

[1990s+] (US prison) innocent of a crime; too clever to get caught, even though guilty.

slick-leg (v.)

[1960s+] (gay) to rub one’s penis against the thigh of one’s sexual partner; thus slick-legging n.

slick shit (n.) [shit n. (3i)]

[1950s+] (orig. US black) any clever stratagem that gets one what is desired.

In phrases

half-slick (adj.)

[1950s–60s] (US) stupid or reckless.

slick as owl shit (also slick as a biscuit, ...a button, ...a greased pig, ...a greased rope, ...an eel, ...a piece of chalk oiled at both ends, …a ram-cat, ...a ribbon, …a school-marm’s leg, ...a smelt, ...a whistle, …cat-shit, ...shit through a goose, ...snot on a door knob, …two snakes fucking in a barrel of snot)

1. [mid-19C+] (US) very smooth(ly), very slick(ly) .

2. [1910s] (US) attractive, good.