Green’s Dictionary of Slang

(Irish/N.Z.) drunk.

1770		Gent.’s Mag. 559: To express the condition of an Honest Fellow, and no Flincher, under the Effects of good Fellowship, it is said that he is [...] Castaway.
1949		P. Newton High Country Days 116: It was not long before he was discovered ‘cast’, and dead to the world, out on the grass in front of the hotel [DNZE].