Green’s Dictionary of Slang

(US) a stupid girl or woman.

1922		Appleton Post-Crescent (WI) 1 May 9/1: Flapper Dictionary bozark – A stupid girl.
1922		Davenport Democrat and Leader (IA) 28 May 32/2–3: I [...] sluffed him for a fluky corn-shredder with a flat tire, who ditched his bozark, to do my corn-crackin’.