Green’s Dictionary of Slang

a blow to the cheek.

1825		Pierce Egan’s Life in London 10 July 189/1: Cooper napt another cheeker, George [...] put in a severe ribber.
1848		Bell’s Life in Sydney 18 Mar. 1/4: Terry got home with a cheeker.
1856		Bell’s Life in Sydney 1 Nov. 3/2: William having imprinted a ‘cheeker’ upon the sheepskin cover presented to him .