Green’s Dictionary of Slang

1. (US) bootleg whisky.

1972

Atlanta Letters n.p.: Moonshine, shine, blue gum, or stump water — home made whiskey, bootleg [DARE].

2. a person of mixed Indian, white and black ancestry.

1970		in DARE.
2010		L. Berney Gutshot Straight [ebook] ‘Shoot him, you dumb fucking blue-gum shine or — ’.