Green’s Dictionary of Slang

ballface n.

[? ballface(d) (whisky) n.]

(US black) a white person.

[US] (ref. to 1810–20) Maledicta VII 27: In Boston about 1810–20, blacks called whites ball face. 1 speculate it is from ‘ball face’ or ‘bald face,’ the name of a whiskey in the same period.