Green’s Dictionary of Slang

loony adj.

also looney, luny
[loony n.]

1. [mid-19C+] (orig. US) eccentric, insane, foolish, pertaining to psychiatry.

2. [1970s+] (US campus) intoxicated.

In compounds

loony bird (n.) [bird n.1 (3a)]

[1960s–70s] (US) a crazy person.

loony-boob (n.)

[1900s] (Aus.) a psychiatric institution.

loony factory (n.)

[1900s] (US) a psychiatric institution.

loony farm (n.)

[1970s+] (US) a psychiatric institution; also in fig. use.

loony house (n.)

[1910s+] (US) a psychiatric institution.

loony pen (n.)

[1980s+] (US) a psychiatric institution.

loony roost (n.)

[1940s] (US) a psychiatric institution.