Green’s Dictionary of Slang

(Aus./N.Z.) to befriend; thus cobbery adj., friendly.

1918		Kia Ora Coo-ee 15 June 4/1: I’ve cobbered up with the bloke on guard here; he yaps a bit of English, so tells me all about you.
1938		X. Herbert Capricornia (1939) 364: What you cobberin’ up with that yeller shisser for?
1959		G. Slatter Gun in My Hand 51: He’s pretty cobbery with some of the owners and trainers.
1968		G. Slatter Pagan Game (1969) 161: Nobody could make head nor tail of it unless he had been cobbery with them for years.
1971		N. Armfelt Catching Up 125: I knew from when you first came that we’d cobber up beaut.
1988		McGill Dict. of Kiwi Sl. 29/2: cobber up with make friends with; eg ‘I cobbered up with Barry over the duck-shooting season, but I haven’t seen him since.’.
2003		McGill Reed Dict. of N.Z. Sl. [as cit. 1988].