Green’s Dictionary of Slang

(Aus.) banter, chat.

1892		H. Lawson ‘Billy’s “Square Affair”’ in Roderick (1967–9) I 225: He knew the kind of barrack that can fetch a square affair.
1907		Sun. Times (Perth) 21 July 4s/3: It’s then it dawns upon your mind, although you’re not a fool, / That you’ve done the graft and ‘barrack’ while the skiter scooped the pool.
1920		Advocate (Burnie, Tas.) 5 June 7/2: At that cricket match the ‘barrack’ was free and fanciful.