Green’s Dictionary of Slang

1. strong home-brewed or cheap liquor, usu. gin.

1893		Dly Public Ledger (Maysville, KY) 27 Jan. 1/4: A Western cowboy staggering [...] under the combined pressure of a seventy-pound Gatling gun and six cubic yards of Jimtown’s stimulating panther’s milk.
1907		Staunton Spectator (VA) 18 Oct. 2/6: Some officials cannot transact business unless they are ‘tanked up’ on panther blood liquor.
1929		‘Wet Words in Kansas’ AS IV:5 386: Panther-sweat, monkey-swill and rat-track whiskey are less easily classified.
1936		(ref. to 1850s) Mencken Amer. Lang. (4th edn) 568: It is to those days before the Civil War that we owe many of the colorful American terms for strong drink, still current, e.g., panther-sweat, nose-paint, red-eye [...] and so on.
1939		in W.C. Fields By Himself (1974) 336: Give me a shot of that panther.
1941		M. Prenner ‘Drunk in Sl.’ in AS XVI:1 Jan. 70/2: liquor [...] panther sweat.
c.1943		‘Bill O. Lading’ You Chirped a Chinful!! n.p.: Panther Blood: Raw liquor.
1946		T. Heggen Mister Roberts 134: That whiskey they make [...] is really panther-piss.
1961		(con. early 1950s) J. Peacock Valhalla 440: One bottle Lucky Tiger Beer and a double shot of panther piss.
1968		G. Slatter Pagan Game (1969) 149: He stood fondling a bottle of his Panther Purge.
1970		N. Beagley Up and Down Under 80: Pure Panther’s piss, brewed in wood.
1980		E. Folb Runnin’ Down Some Lines 187: Hard liquor also had its own vernacular labels [...] panther piss and white lightning for home brew.
1992		R.C. Cruz Straight Outta Compton 19: Panther piss is this funky, yellowish cheap booze that is so nasty it makes you want to puke.
2001		J. Manning Mountain Vengeance 306: ‘This panther piss tastes good.’ [...] ‘I guess anything would after a few weeks with nothing but water to drink.’.

2. nonsense.

1957

T.T. Chamales Never So Few (1958) 348: ‘Maybe he tightened up.’ ‘Panther piss,’ Mark said. ‘He was loose as a rag that day.’.