Green’s Dictionary of Slang

(US) cheap or illicitly distilled bourbon.

1858		Southern Literary Messenger XXVII 463/2: A rough, but hearty frolic, characteristic of the time and place, with rustic ‘jigs’ and ‘hoedowns,’ and profusion of ‘pine-top’ succeeded .
1864		in B.L. Ridley Battles and Sketches of the Army of Tennessee (1906) 446: Instead of flasks of gin, we found something else, ‘not pine top,’ nor ‘Confederate pop skull,’ nor ‘Jeff Davis bust head,’ but great heavens! peach brandy.
1874		St Mary’s Beacon (Leonard Town, MD) 15 Nov. 2/4: The ‘boys’ [...] drinking small portions of ‘pine-top’ juice, turning somersaults blindfolded over empty wine [...] casks.
1880		Public Ledger (Memphis, TN) 14 Feb. 2/4: I believes I’ll take some moah ob dat pine top whiskey.
1888		Pacific Commercial Advertiser (Honolulu, HI) 22 Aug. 3/4: Pure ‘Pine-Top’. It’s pine-top whiskey it is! Why, dog-gone it, it’ll fire ye up.
1905		Rice Belt Jrnl (Welsh, LA) 23 June 4/1: We blowed another quarter on [...] twom drinks of ‘pine-top,’ ‘blind tiger’ liquor.
1910		Bulletin (Sydney) 13 Oct. 19/3: Amongst these sinful fabrications may be mentioned [...] pinetop and tobacco (a poisonous preparation used by negroes in prohibition territory in the South).