Green’s Dictionary of Slang

(US) a scatterbrained person; also as a term of address.

1988		Eble Campus Sl. Oct. 3: ditzo – airhead [...] She can be such a ditzo sometimes.
1999		Bob & Miles ‘Guns’ at Rosebud mag. [play script] 🌐 Morris: [...] Now get the hell out of here. (Both Jasper and Keri begin to back toward the door.) Not you, ditzo. This is your office.
2002		D.J. Belt Tomb Ch. iii 🌐 ‘Hold on, Jan, I didn’t find this.....your graduate student, Sallie, did.’ ‘Sallie? That...ditzo..... found this?’ Jan was incredulous.