Green’s Dictionary of Slang

king adj.

(Aus./US) excellent, wonderful, perfect.

1870		White Cloud Kansas Chief (KS) 11 Aug. 1/4: 4000 caricatoor portrates uv Chase [...] inskribed ‘The King nigger lover’ .
1909		J. Washburn Und. Sewer 58: Every city has its king gambler.
1911		E. Dyson ‘An Amorous Boy’ in Benno and Some of the Push 175: ‘Now yiv got it,’ he said to the packer. ‘Iv it ain’t the king stinker boy, pickle me.’.
1984		J. Ellroy Blood on the Moon 158: ‘You are the king fucking dick of Boy's Town because [...] I shoot you the dope and the protection that make you and your punk pals a class act’.
1967		‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxv 6/3: king: Same as grouse, meaning very good.
1993		Eble Campus Sl. Oct.
2003		McGill Reed Dict. of N.Z. Sl. 121: king fleece/mate/tide/tree, etc Any object rated tops, though not always with approval [...] early C20.

In compounds

king-hell (adj.) [on pattern of terms like king hit n.; or abbr. fucking hell!]

(orig. US) formidable, impressive.

1966		H.S. Thompson Hell’s Angels (1967) 143: The scene had all the makings of a king-hell brawl.
1977		in H.S. Thompson Great Shark Hunt (1980) 22: You bastards are going to owe me a king-hell forty-four-gun salutr (that word is ‘salute’, goddamnit).
1985		(con. 1968) D.A. Dye Citadel (1989) 300: Where’s the heavyweight, king-hell recriminations?
2001		J. Stahl Plainclothes Naked (2002) 245: Zank [...] pulled a king-hell hit, exhaled fast, and whipped his head toward the window.