Green’s Dictionary of Slang

ka-zip n.

In phrases

off one’s kazip (adj.) (also off one’s kerzip) [ety. unknown]

(US) insane, eccentric.

[US]‘O. Henry’ in Works 257: ‘You’re off your kazip,’ declared another of the gang.
[US]L.W. Payne Jr ‘Word-List From East Alabama’ in DN III:iv 290: be off one’s base, (box, kerzip, nut), v.phr. To be out of one’s mind. ‘You’re offn your kerzip if you think I’d do that.’.
[US]Ocala Eve. Star (FL) 26 June 2/1: Editor Lightfoot [...] is evidently off his ‘kazip’ when he says Genweral Gilchrist was niminated [...] because he opposed prohibition.
Clinch Valley News (Jeffersonville, VA) 25 Feb. 2/3: There is a mistake. John Hart could not make such a statement [...] Some body was off his kazip.
[US]D. Runyon ‘Broadway Financier’ in Runyon on Broadway (1954) 208: A young guy [...] goes right off his ka-zip about her.
B. Halliday Uncomplaining Corpses 145: He had gone off his kazip and said some things he didn't mean up there in the apartment.