Green’s Dictionary of Slang

Jew chum n.

1. (Aus.) a Jewish refugee from Germany or central Europe [pun on new chum n. (2)].

[Aus]Baker Popular Dict. Aus. Sl.
[UK]J. Franklyn Dict. of Rhy. Sl.

2. (US) a tramp [rhy. sl. = bum n.3 (2)].

[US]Maurer & Baker ‘“Aus.” Rhyming Argot’ in AS XIX:3.