Green’s Dictionary of Slang

(Aus. prison) to share; thus waxer n., one who is entitled to a share.

1984		B. Ellem Doing Time 199: wax: to share commodities with another [...] waxer: the person with whom a prisoner shares.
1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Wax. To share. [Ibid.] Waxer. A person entitled to a share or benefit.
2005		M.B. ‘Chopper’ Read Chopper 4 37: How do I explain the meaning of the word ‘waxer’? It is a mainland old-time jailhouse slang expression, meaning something like: ‘I’ve got the sugar, you’ve got the coffee, so lets join forces for a cuppa.’.