Green’s Dictionary of Slang

(US black) a guitar.

1981		R. Sykes in Levet Talkin That Talk (2010) 89/1: People used to call guitars ‘starvation boxes’.
1992		(con. 1917) Wolfe & Lornell Leadbelly 67: He admonished Leadbelly about the fast life and the ruination that his ‘starvation box’ — his guitar — would bring.
2000		J.L. Hooker in Levet Talkin That Talk (2010) 89/1: Sje used to tell me, ‘You ain’t never gonna get nowhere with this ol’ git-tar, ol’ starvation box.
2012		(con. early 1950s) Taj Mahal in Crowe My First Guitar [ebook] She and my friend Garland’s mother called the guitar ‘a starvation box.’ ‘You still up there playing that starvation box?’.