Green’s Dictionary of Slang

Murray cod n.

In phrases

on the Murray cod (v.) [rhy. sl. = nod n.1 (2)]

(N.Z. prison) comatose from a given narcotic drug.

[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 120/2: on the Murray Cod n. under the influence of intravenous drugs.