Green’s Dictionary of Slang

nutso adj.

[nutso n.]

(orig. US) stupid, unstable, eccentric.

M. Saunders Phonograph Rec. Apr. [Internet] You may think I’ve gone nutso, but I don’t care; Yoko has gotta be one of the new talents of the year, and hands down the finest female rock ’n’ roller since the Shangri-Las.
[UK]Guardian Guide 15–21 May 21: Nutso German director Werner Herzog.
[US]S. King Dreamcatcher 498: He’ll break out and do something nutso.
twitter 23 June [Internet] Terrific AP fact-checking of Trump’s wild accusations. Question. Why isn’t every paper doing this instead of parroting his nutso assertions?