Green’s Dictionary of Slang

(Aus.) a tell-tale; a ‘whistleblower’.

2001		Canberra Times 5 Feb. T11: Perhaps being a mama’s boy and dibber-dobber could be counted on Ray’s good side.
2002		Daily Tel. (Sydney) 4 May 2: An anonymous ‘dibber dobber’ with tales of secret meetings and contract rigging has delivered the power industry one of Australia’s biggest price-fixing penalties. Like the whistleblower who alerted the Australian Competition and Consumer Commission to alleged price fixing in the petrol market, an unnamed informant has helped out again.