Green’s Dictionary of Slang

(Aus.) to mock, to tease.

1885		Bulletin (Sydney) 25 Apr. 10/1: And what has this young gentlemen been doing to be so deprived of sweetness and light and the songs of birds and the innocent delights of expectorating on street corners and gaily ‘borraking’ the passers-by?
1933		L. Stone Larrikin 306: Borak – to poke malicious fun.