Green’s Dictionary of Slang

1. (N.Z. prison) marijuana [‘As one inmate explains ‘When you take it, you’re “gonner” get wasted, and once you have taken it, you’re a “gonner”’ Looser (2001)]].

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 80/1: gonner n. marijuana.

2. see goner n.¹