Green’s Dictionary of Slang

bombo n.1

[SE bomb + -o sfx (3); it ‘knocks one out’. Note SE bumbo, ‘A liquor composed of rum, sugar, water and nutmeg’ (OED)]

1. [1940s+] (Aus.) cheap wine, methylated spirits or a combination of the two.

2. see bumbo n.1

In compounds

bombo-basher (n.)

[1940s] (Aus.) a (usu. street-level) alcoholic.

bombo joint (n.)

[1940s] (Aus.) a shanty or public house that sells cheap wine and/or methylated spirits.