Green’s Dictionary of Slang

1. (US) to knock someone unconscious.

1801		C. Dibdin Yngr Song Smith 85: So they sent out of hand for the clargy to lay him, / But Pat laid the clargy, and then ran away.
1836		in Spirit of the Times (N.Y.) 9 July 162: You’ll lay him cold as a wagon tire [HDAS].
1890		Sporting Times 3 May 1/5: NO HORSEPOUTS. PUT UP YOUR DOOKS. ME LAY YOU! GARN.
1934		(con. 1920s) J.T. Farrell Young Manhood in Studs Lonigan (1936) 291: He [...] imagined himself just walking up to them one by one, and laying them cold.

2. (US black) to idle, to relax, to spend time with.

1967		P. Thomas Down These Mean Streets (1970) 5: I laid cool. Even my breathing was cool.
1974		V.E. Smith Jones Men 16: I don’t mind laying a minute for that white-bag shit.
1993		E. Richards Cocaine True 136: She lay out with them dummies who shoot drugs.

3. (US black) to over-indulge in drugs or drink to such an extent that one is laid on one’s back.

1983

R. Klein Jailhouse Jargon and Street Sl. [unpub. ms.].