Green’s Dictionary of Slang

1. a young man, often used affectionately by an older man to a younger one.

1986

Chapman NDAS.

2. an Italian man.

1942		N. Algren Never Come Morning (1988) 72: An Italian who nobody knew [...] scurried off down the alley. ‘I wasn’t lettin’ no wallio in on this,’ Bruno assured everyone.
1947		N. Algren Neon Wilderness (1986) 83: We was doin’ guys we never seen before even, Wallios ’n Greeks ’n a Flip from Clark Street.
1975		E. Torres Carlito’s Way 6: Earl Bassey, a black dude, and Rocco Fabrizi, a wal-yo.
1988		H. Gould Double Bang 57: You sure ain’t gonna trust no wallyo to keep your secret like this nigger does.