Green’s Dictionary of Slang

lukshen n.

also loksh, luksh
[Yid. lokshen, noodles, in this context pasta]

(US Jewish) an Italian.

[US]H. Robbins A Stone for Danny Fisher 106: She was a strange kid for a luksh. Usually they were loud and tough and you could tell they were Italian as soon as they opened their mouths.
[US]Maledicta VII 23: In Yiddish-American slang, an Italian was a lukshen and loksh, Yiddish for noodle, i.e. spaghetti.