Green’s Dictionary of Slang

(Aus.) a bottle of alcohol.

1891		Truth (Sydney) 5 Apr. 7/3: The riding men [...] frequently come home rolling from side to side and with a poddy in their kick [AND].
1953		H.M. Eastman Memoirs of Sheepman 58: For anaesthetic he would use a couple of ‘poddies’ (lemonade bottles of whisky) obtained from Coree pub [AND].
1968		A. Burgess Enderby Outside in Complete Enderby (2002) 313: And then more of Ricker Sugden - ‘The Ditty of the Merry Poddyman,’ ‘Wallop for Me Tomorrow Boys’ .