Green’s Dictionary of Slang

shake n.2

also shaker
[? shade n.1 (4a) or play on chocolate milkshake]

(US) a derog. term for a black person.

[US]Coshocton (OH) Daily Age 22 June 6/4: It’s only the hurry-up wagon for a couple of shakes that was fighting [...] you know what shakes – shakers – are. They’re coons.