Green’s Dictionary of Slang

excellent, first-rate.

1975		A. Bleasdale Scully 144: ‘Cracker, Mooey,’ I said [...] ‘We’re on our way home.’.
1988		McGill Dict. of Kiwi Sl. 31/2: cracker excellent, highly approved.
1998		K. Sampson Awaydays 9: Howdy, Danny. Cracker mob, eh?
2003		McGill Reed Dict. of N.Z. Sl. [as cit. 1988].
2018		C. Hammer Scrublands [ebook] Cracker interview with local cop.