Green’s Dictionary of Slang

lay down v.

1. in senses of giving up [boxing imagery].

(a) [late 19C+] (US, also lay to, lie down) to volunteer for defeat; thus lay-down artist, a defeatist.

(b) [1910s+] to collapse.

(c) [1930s+] to accept, to acquiesce.

2. [1930s–60s] (drugs, also lay, lie down) to smoke opium [the smoker’s recumbent position].

3. [1930s+] (US prison) to place an inmate in the punishment cells [punishment cells were so cramped there was barely enough room to stand upright].

4. [1940s+] (US) to explain, to outline, to present a theory.

5. [1950s] (Aus. Und.) to retract a confession or witness statement.

In compounds

lay-down joint (n.) [joint n. (3a)]

[1930s+] (US drugs) a place to smoke opium.

In phrases

lay down on (v.)

[late 19C+] (US) to abandon someone, to fail in a duty.

SE in slang uses

In phrases

lay down one’s knife and fork (v.) (also chuck in one’s knife and fork)

[mid-19C–1930s] to die.

lay down (on one’s/the job) (v.) (also lie down (on the job)) [1910s+] (orig. Aus.)

to act lazily; to do a job badly.

lay down some cow (v.)

see under cow n.1

lay ’em down (v.)

1. [1930s–40s] (US) to die [one ‘lays down’ one’s body].

2. [1940s+] (US) to drive very fast [the pressing down of the accelerator].