p.i.g.s., n. — Green’s Dictionary of Slang

p.i.g.s. n.

[abbr.]

(US) Poles, Italians, Greeks and Slavs.

1996		P. Coclanis on Reason Online 🌐 It was a close-knit ethnic enclave populated by lots of what Michael Novak calls PIGS—Poles, Italians, Greeks, and Slavs.
2004		‘The Lang. of Pittsburgh’ at pittsburgh.about.com 🌐 We have Germans, Poles, Italians, Slovaks, and a dozen other nationalities.