Green’s Dictionary of Slang

(US) a whipping.

1827		Amer. Sentinel 21 Apr. 3/2: Hickory oil is the grand restorative [DA].
1857		Southern Literary Messenger XXV 306/1: At school he is a disciplinarian of the strictest old-fashioned style; dosing small boys with hickory oil [DA].
1916		John Massey Reminiscences 47: Mr. Hennessee taught the ‘three R’s’ very thoroughly, as was reported, by the lubrication of ‘hickory oil’ [DA].
1939		P.G. Brewster ‘Folk “Sayings” From Indiana’ in AS XIV:4 267: An obstreperous youngster is likely to be dosed with ‘peach tree tea,’ ‘hickory tea,’ or ‘strap oil,’ or by some other means forced to ‘walk the chalk’ and to ‘toe the mark’.
1953		Randolph & Wilson Down in the Holler 251: hickory-limb oil: n. A whipping.