Green’s Dictionary of Slang

borak n.

also borac, borack, borax
[Wathawurung burag, no, not, via. Aus. pidgin borak, used to express negation]

[mid-19C+] (Aus./N.Z.) nonsense, humbug, chaff, banter.

In compounds

borak merchant (n.)

[1970s] (Aus.) a persistent tease.

In phrases

poke (the) borak (v.) (also …borack, …borax, poke it)

[mid-19C+] (Aus./N.Z.) to make or poke fun.