Green’s Dictionary of Slang

1. (US) illicitly distilled whisky; also as attrib.

1857		Richmond Enquirer 20 Noov. 2/5: [B]oth parties were drinking a beverage known in the locality as ‘pop skull whiskey’' at the time of the affray.
1859		Edgefield Adverrtiser 16 Feb. 3/2: Nor would corn whiskey [...] constitute as it now does most of the wines which we drink. Besides less ‘Pop Skull’ would then be used, and the health of our people would be promoted.
1864		in B.L. Ridley Battles and Sketches of the Army of Tennessee (1906) 446: Instead of flasks of gin, we found someting else, not ‘pine top,’ nor ‘Confederate pop skull,’ nor ‘Jeff Davis bust head,’ but great heavens! peach brandy.
1867		G.W. Harris Sut Lovingood’s Yarns 222: He jis’ grabbed a bottil, an’ tuck hissef a buckload ove popskull.
1929		‘Wet Words in Kansas’ AS IV:5 386: Such terms as [...] pop-skull and bust-head are evidently references to the potency or the effect of the liquor designated.
1931		A. Hardin ‘Volstead Eng.’ in AS VII:2 87: Terms used for intoxicating liquor: Pop skull.
1941		‘More Tennessee Expressions’ in AS XVI:1 Feb. 447/2: popskull. Low grade liquor. ‘He’s crazy on popskull.’.
1943		M. Constiner ‘The Turkey Buzzard Blues’ in Ruhm Hard-Boiled Detective (1977) 268: I favor popskull moonshine.
1957		Miami News (FL) 7 Nov. 128/3: [headline] ‘Popskull Is Skull Popper. [...] A bottle of liquor taken from a prisoner ‘exploded like a stick of dynamite’.
1964		A. Hine Unsinkable Molly Brown 24: Gert [...] helped herself to a six-finger helping of Hank Kimmel’s best popskull.
1971		T. Thackrey Thief 34: I put some of that green corn popskull in me.
1986		S. King It (1987) 86: The local popskull is pretty potent.

2. any form of strong drink.

1943		J. Mitchell McSorley’s Wonderful Saloon (2001) 147: He mixes gin with Pepsi-Cola, half and half, and calls the mixture old popskull.
1982		M. Braun Judas Tree (1983) 60: He thought a drink might wash away the cobwebs. A shot of popskull was known for its restorative effects.

3. (US gay, west.) man-to-man fellatio.

2022

(con. late 19C) J. Nevins ‘Western frontier gay slang’ on Twitter 2 Mar. 🌐 ‘pop skull’ = liquor or oral sex.