Green’s Dictionary of Slang

1. the head.

1838

J. Grant Sketches in London 173: They thought there was a screw loose in the upper part of my machinery.

2. (US prison) a male homosexual [machine n. (1)].

1931–4

D. Clemmer Prison Community (1940) 333/2: machinery, n. An invert.

3. (US drugs) the equipment used for injecting a narcotic.

1937		B. Dai Opium Addiction in Chicago.
1949		Monteleone Criminal Sl. (rev. edn).
1959		J.E. Schmidt Narcotics Lingo and Lore.
1971		E.E. Landy Underground Dict. (1972).

4. (US) a (sexually appealling) woman.

1950

R. Starnes Another Mug for the Bier 96: ‘I saw her as I left his apartment. Very well-kept piece of machinery. [...] Very vigorous and healthy-looking tomato’.

5. the male genitals.

1986

C. Stroud Close Pursuit (1988) 33: Guy gets a hand underneath the broad’s skirt and finds out he’s got a boy gobbling on his machinery.

6. (drugs) marijuana.

2001

ONDCP Street Terms 14: Machinery — Marijuana.

7. a revolver, a pistol.

1991

in J. Breslin Damon Runyon (1992) 17: ‘The secret of my success is that i always keep my machinery in good operating condition,’ Bieler told him.