Green’s Dictionary of Slang

motherload n.

[SE motherlode, a principal vein of an ore or mineral, thus a rich source of something ? + mother n. (2)]

(N.Z. prison) a large consignment of contraband.

Show quotations
[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 119/1: motherload n. a large delivery of contraband, a big drop: ‘Bro, I’ve got a motherload coming up today, could you stash it for us?’.