Green’s Dictionary of Slang

1. a hard or knockout blow.

1898		Truth (Sydney) 6 Nov.8/1: [A] shattered nose may vex us, / Or a ‘King hit’ on the plexus.
1905		Sydney Sportsman (Surry Hills, NSW) 23 Aug. 6/5: He decided to enter the ring rather than disappoint tbe audience, hoping to force matters and get home a king hit quick and lively.
1907		Sun. Times (Perth) 30 June 1/1: The feud between the Senior footballer and the milkman grows and gathers [and] he recently got in the king hit on his white-thatched lacteal merchant.
1918		Sun. Times (Perth) 27 Oct. 7/5: The king hit is the hall mark of a rough and tumble fighter.
1924		G.H. Lawson Dict. of Aus. Words And Terms 🌐 KING HIT—The winning blow in a fight.
1941		Baker Popular Dict. Aus. Sl. 41: King hit, a knock-out blow.
1951		D. Stivens Jimmy Brockett 188: ‘Making a fortune, uh?’ he says, eyeing me like a mangy bubonic rat. ‘Making it, and spending it, too.’ That was a king hit. He didn’t like the way I said it.
1961		B. Crump Hang On a Minute, Mate (1963) 164: One king-hit and I was a goner.
1976		D. Ireland Glass Canoe (1982) 24: It was handy to know early if it would be necessary to duck a chair or a king-hit.
1982		G. Newbold Big Huey 250: king hit (n) and (v) Knockout punch.
1983		J. Byrell (con. 1959) Up the Cross 83: He hit Brucie [...] smack on the jaw, then [...] in the ribs. The two king hits didn’t hurt.
1990		A. Duff Once Were Warriors 66: [T]his dude ... packed a punch like a fuckin elephant, how he took on three and dropped the three of em: Pow! Kinghit on the first one.
1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 King hit. A preemptive blow of considerable force designed to take one’s adversary out of action. Often administered surreptitiously.
1999		D. Looser ‘Boob Jargon’ in NZEJ 13 32: king hit n. 3. A direct punch to the face.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 100/1: king hit n. 4 a knockout punch, achieved by any of the above.
2005		P. Temple Broken Shore (2007) [ebook] Three English backpackers [...] giving some local hoons cheek. One took a king hit, went down and stayed down.

2. (also king punch) a surprise punch or attack; thus king-hit merchant.

1905		Eve. News (Sydney) 19 Jan. 5/1: As Rodoni entered the room , M’Glue landed him ‘one’ on the face [...] M’Glue said he thought Rodoni was going to interfere (i.e. in a domestic argument) and he ‘got in the “King” hit’.
1951		D. Stivens Jimmy Brockett 203: All the week I had been laughing up my sleeve fit to kill, and then last night I decided to let ’em have the king hit.
1975		Bulletin (Sydney) 26 Apr. 46: You wouldn’t believe some mug picked Punchy for a mark and barrelled a king at him at the bar.
1981		G. Johnston Fish Factory 48: A damned shame indeed for a man who’d scrapped enough in the past to normally avoid the receiving end of [...] a king-hit.
1992		R.G. Barrett White Shoes 234: It wasn’t so much a king-hit, Norton’s massive fist nearly took Jasper’s head off.
1999		D. Looser ‘Boob Jargon’ in NZEJ 13 32: king hit n. 1. An attack from behind. 2. A cowardly assault.
1999		G. Seal Lingo 119: Definitions and some usages of the term refer to a king hit as a pre-emptive punch or blow, often an unfair or unexpected one. While this may be so, the term is used of a type of blow involving the clenching of the assailant’s hands into a club of hard flesh that is brought down on the unfortunate receiver’s face or upper back.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 100/1: king hit n. 1 an attack from behind 2 a cowardly assault. 3 a totally unexpected punch (usually directly to the face) [...] 101/1: king punch n. = king hit sense 3 .
2004		(con. 1960s-70s) T. Taylor Top Fellas 25/1: A lad called the Beast, who was a notorious king-hit merchant.

3. (N.Z. prison) an attack in which despite having acheived a knockout, the attacker continues to punch his victim.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 100/1: king hit n. 5 a fighting tactic in which the aggressor knocks his opponent out with a single punch, and then continues to hit him .