Green’s Dictionary of Slang

nut house n.

[nut n.2 (1) + SE house]

1. [1920s] (US) a mad person.

2. (orig. US, [1910s+] also nut hospital) a psychiatric institution.

3. attrib. use of sense 2.

4. [1930s+] (US) a chaotic place or situation, a fig. madhouse.