Green’s Dictionary of Slang

(US black) one who is mixed-race, black and white.

1972		B. Rodgers Queens’ Vernacular 63: graham cracker (black gay sl, ’72) crumbling Uncle Tom.
2000		Ebonics Primer at www.dolemite.com 🌐 graham cracker Definition: someone who is half of any color, and half white. Example: Man, that aint no nigga, dat busta is a fuckin graham cracker.