Green’s Dictionary of Slang

a dead person.

1973		(con. 1969) Karlin, Pacquet & Rottmann Free Fire Zone 85: You laugh at the deadies.
1997		Begbie007 ‘Now irradiate your hands’ (poem) in Gazpacho Soup III 25 Nov. 🌐 Rimmer, I knew him, a man of infinite jest, and most excellent, merriment, where be your jibes, and jests now laddy, your career, ended, before it started, / and now, your just a deadie.