Green’s Dictionary of Slang

dig in the grave v.

(Aus. prison) to divide up spoils.

[Aus]Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Dig in the grave. 1. Have a share of the spoils.
[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 55/2: dig in the grave v. to shave.