allo, adj. — Green’s Dictionary of Slang

allo adj.

[pidgin; the -o sfx makes up for the lack of a final ‘l’ in Chinese speech]

all.

1889–90

Barrère & Leland Dict. of Sl., Jargon and Cant 29/1: Slang-Whang when makee noise, / Wit’ he pigtail floggee allo boys, / Allo this pidgin long time ’go, / What time good olo Empelor Slo.