Green’s Dictionary of Slang

(US teen/campus) pizza; thus do a za, to buy or eat a pizza.

1968		Current Sl. III:1 15: Za, n. Pizza.
1979		Eble Campus Sl. Mar. 4: Let’s go for ha-ha’s and za.
1982		W. Safire What’s The Good Word? 302: You guys want to go in on a za?
1992		N. Stephenson Snow Crash (1993) 8: That means high turnover for him, fast action, keep moving that ’za.
1999		Eble Campus Sl. Nov.