Green’s Dictionary of Slang

(US tramp) a handout of cold food, e.g. a sandwich.

1925		G.H. Mullin Adventures of a Scholar Tramp 14: Her parcel is known in Hoboland as [...] a ‘poke-out,’ or a ‘dukee’.
1950		Goldin et al. DAUL 63/2: Dukee. 1. (Hobo) A handout of cold food, usually a sandwich, piece of pie, etc.