Green’s Dictionary of Slang

Kentucky adj.

[geographical and/ or social stereotyping]

(US) pertaining to violence.

[US]N.-Y. American 1 Nov. 2/5: One of these lawless intruders, who, probably excited by an over dose of blue ruin, was disposed to be troublesome and impertinent, received from one of the drivers of the hunt his pay down, in undepreciated Kentucky currency, producing a total obscurity of his day-lights and a most copious effusion of claret.
[US]N.-Y. Eve. Post 21 Sept. 2/2: I saw no less than four fights in as many minutes, conducted in the Kentucky style of rough and tumble.

Based on negative connotations of the state

In compounds

Kentucky argument (n.)

(US) a dispute which escalates to the drawing of firearms.

[US]Sunbury American (PA) 17 Apr. 2/5: The bowie knife is a conspicuous agent in almost every Kentucky argument.
[US]Lantern (N.O.) 16 July 5: There was a Kentucky argument, one drawing a revolver on the other.
[US]Hartford Repub. (KY) 23 June 8/1: [headline] A Kentucky Argument. Close Call for Everybody, but of Course no Ladies were Hurt.
Kentucky bite (n.)

(US) a cutting bite to the ear or nose during a fight.

[US]N. Ames Mariner’s Sketches 147: It was not difficult to perceive that in the Indian hug or Kentucky bite, I should stand no chance at all [DA].
[US](con. 1843) Melville White-Jacket (1990) 105: Sparring and wrestling, too, were all the vogue; Kentucky bites were given, and the Indian hug exchanged.
Kentucky blue (n.) [joc. ref. to Kentucky blue grass]

(US drugs) a variety of marijuana grown in Kentucky.

[US]L. Kramer Faggots 301: Moroccan Hash, Red Lebanese, Black Afghani, Hawaiian, Kentucky Bluegrass.
[US]ONDCP Street Terms 13: Kentucky blue — Marijuana.
Kentucky breakfast (n.) [the supposed favourite breakfasts of the classic ‘Southern gentleman’] (US)

1. popularly defined as ‘three cocktails and a chew of terbacker’.

[US]Louisville Medical News (KY) 1 Dec. 254: a "simple Kentucky breakfast" as consisting of ‘three Stimulants, and a chaw of tobacco’.
[US]Century Mag. (NY) Apr. 884/2: He traveled with a dusky valet, a silver-headed cane, two ruffled shirts, and a case of hair-triggers. His morning meal was a simple Kentucky breakfast—‘three cocktails and a chaw of terbacker’ .
[US]Princeton Union (Minn.) 7 May 2/4: ‘What is a Kentucky breakfast, sir?’ Mr Watterson gazed pityingly at the chef [...] ‘Two drinks of whisky and a chew of tobacco’.
[US]St Paul Globe (Minn.) 7 May 5/5: Lentucky Breakfast Food [...] ‘He’s gone up to Michegan to work in one of them thah breakfas’ food places. All he has to do is to put the breakfas’ food in o’ of these hyah pas’ebo’d boxes’ [...] ‘How in time can a man git a chew o’ tubacker an’ a jiggeh o’ whisky in a pas’ebo’d box so’s hit won’t spill?’.
[US]New Eng. Soc. Annual Report 99-102 56: The Southerner [...] whose morning meal consisted of a simple Kentucky breakfast, three cocktails and a chaw of tobacco.
[US]Wash. Times (DC) 26 Jan. 10/5: The standard Kentucky breakfast [...] is simple, manly, stimulating [...] Rise at 5.30 a.m.: three cocktails; a chew of tobacco; coffee.

2. a bottle of bourbon, a three-pound steak and a setter dog or bull-dog; the dog is there to eat the steak.

[US]S.E. White Arizona Nights 117: What’s a Kentucky breakfast? Why a Kentucky breakfast is a three-pound steak, a bottle of whisky, and a setter dog. What’s the dog for? Why, to eat the steak, of course.
[US]Day Book (Chicago) 12 Dec. 21/2: ‘Waitah,’ said Col. Clay [...] ‘you-all kin bring me a Kentucky breakfast.’ ‘And what is that, sir?’ asked the waiter. ‘Bring me a big steak, a bull-dog and a quart of bourbon whisky.’ ‘But why do you order a bull-dog?’ asked the waiter. ‘To eat the steak, sir,’ replied the colonel.
[US]Ogden Standard (UT) 17 Aug. 14/3: ‘What have you for breakfast?’ ’Ain’t but one kind of Kentucky breakfast,‘ the old negro replied a grin [...] ‘Jug of liquor, ar nice steak, an’ ar dog’.
Kentucky bustle (n.)

(US) a form of belt worn beneath the clothes and used to carry contraband liquor.

[US]L.A. Times 15 Aug. 25/2: Colored valet has New Name for Hip Adornment [...] ‘He had a Kaintuicky bustle on both hips [...] stuffed with good old corn juice from Louisville’.
Kentucky oysters (n.)

(US, mainly black) chitterlings, pig intestines.

[US]Paducah Daily Sun (KY) 18 Jan. 3/6: The Bethel Club gives a ‘Kentucky Oyster’ At the [...] church tonight.
[US]P.L. Dunbar Folks from Dixie 103: There was hog jole and cold cabbage, ham and Kentucky oysters, more widely known as chittlings.What more there was it boots not to tell .
[US]Frankfort Roundabout (KY) 26 Dec. 7/4: ‘Hog oysters,’ or ‘Kentucky oysters,’ as the succulent chittterlings of the festive porker are sometimes called, are all the rage.
[US]Appeal (St Paul, Minn.) 6 Dec. 4/2: The Willing Workers’ Club [...] will host a ‘Kentucky Oyster’ (chitterling) supper.
D. Burley in Chicago Defender 7 Nov. 6: I take it that you mean chitterlings when you say Kentucky Oysters.
Kentucky tea (n.)

four parts water, one part bourbon.

B. Noe in Pittsburgh Post-Gaz. 20 Apr. 🌐 Maybe the most authentic way to enjoy [bourbon] is by mixing ‘tall water’ in honor of bourbon luminary Booker Noe: one part Booker's to four parts water. As Booker used to tell everyone, it's just ‘Kentucky tea.’.
Kentucky treat (n.) (also Kentucky)

(Aus./US) a supposed ‘treat’ for which everyone present has to contribute.

[US]H.R. Mighels Sage Brush Leaves 260: I detect Ex-Congressman Piper taking a monobibe — which is a word I have invented to embody the lonesome idea of a solitary drink — a ‘Kentucky’ treat: not that I wish Piper would treat me.
[US]T.W. Knox Teetotaller Dick 335: I’ve heard a ‘Kentucky treat’ spoken of as a treat where each man pays for his own drinks.
[US]DN IV 420: Kentucky treat, n. Same as Dutch treat.
[Aus]N. Pulliam I Travelled a Lonely Land (1957) 235/1: Kentucky – the money everyone chips in to ‘go dutch’ on a party.