Green’s Dictionary of Slang

screw n.2

[a screw loose under screw n.1 ]

a mad person.

[US]W. Brown Run, Chico, Run (1959) 31: Tomas is a screw. He don’t like boom.

In compounds


see separate entries.

screw factory (n.)

a psychiatric hospital.

[US]J. Wambaugh Choirboys (1976) 207: Mrs. Bloomguard [...] did a naked tap dance in front of the Pomona courthouse and had to be taken to the screw factory to get rethreaded.

In phrases

loose screw (n.)

an eccentric.

[US]Van Loan ‘Ten-Thousand-Dollar Arm’ in Ten-Thousand-Dollar Arm 3: There have been enough peculiar left-handers to justify the belief that side-wheelers and loose screws go together.
[US](con. 1910s) J.T. Farrell Young Lonigan in Studs Lonigan (1936) 6: Girls had loose screws in their beans.