Green’s Dictionary of Slang

(Aus./N.Z.) go away! be off!

1979		Lette & Carey Puberty Blues 11: ‘Ouch!’ I screamed. ‘Oh rack off.’.
1992		K. Lette Llama Parlour 59: ‘Come on, kid. Pay up.’ ‘Rack off.’.
1997		T. Winton Lockie Leonard, Legend (1998) 22: Rack off, Phillip.
2003		McGill Reed Dict. of N.Z. Sl. 168: rack off! Go away! ANZ 1970s.
2016		D. Whish-Wilson Old Scores [ebook] Stormie gave him a look of triumph, followed by the forked fingers. [...] ‘Rack off.’.