peep, v.⁴ — Green’s Dictionary of Slang

peep v.⁴

peep in the heater (v.)

(US) to perform cunnilingus.

c.1935

‘Mae West in “The Hip Flipper”’ [comic strip] in B. Adelman Tijuana Bibles (1997) 95: He had commenced to enjoy peeping in the heater.

peep through one’s liquor (v.)

(US black) to pose as sober when one is in fact drunk.

1942

Z.N. Hurston ‘Story in Harlem Sl.’ in Novels and Stories (1995) 1009/2: Peeping through my likkers — carrying on even though drunk.