kook, n. — Green’s Dictionary of Slang

kook n.

also cook, klookhead, kuke

[? cuckoo n.¹ (2) but popularized following the late 1950s US TV show 77 Sunset Strip in which the supposedly (by 1958 standards) ‘eccentric’ character Gerald Lloyd Kookson III (‘Kookie’), played by actor Edd Byrnes (b.1933), became a teenage idol]

1. (US) a crazy person, an eccentric, albeit an acceptable one.

1956		N. Algren Walk on the Wild Side 83: Broken men and breaking ones; wingies, dingies, zanies and lop-sided kukes; cokies and queers and threadbare whores.
1961		F. Kohner Gidget Goes Hawaiian 27: I spotted Wally and Judge who were surrounded by a bunch of screaming kooks.
1963		C. Wood ‘Prisoner and Escort’ in Cockade (1965) I iii: No wonder Fred went spare – brother to a Kuke.
1965		W. Eastlake Castle Keep (1966) 141: ‘Who do you suspect put it there?’ ‘Some klookhead.’.
1971		W. Burk Thief 421: That was Outer Space, you know? Dingbats? I mean a pack of raving kooks running around.
1984		J. McNamara First Directive (1985) 175: A group of kooks I never heard of.
1990		S. Morgan Homeboy 190: If only the carrottop kook were hunkered beside him.
2007		T. Dorsey Hurricane Punch 191: He was dismissed as one of the kooks the show invites for the regulars to gang up on.
2011		Intelligent Life Spring 128/2: It wasn’t the upright types who defied the Nazis: it was the cranks, the kooks.
2018		Eve. Standard 11 Nov. 11/3: Mrs Obama [...] wrote ‘The whole thing was crazy [...] deliberately meant to stir up the wingnuts and kooks’.

2. attrib. use of sense 1.

1987

‘Joe Bob Briggs’ Joe Bob Goes to the Drive-In 67: So maybe we’re not the kook capital we thought we were.

3. (US) a spy.

1962

S. Longstreet Flesh Peddlers (1964) 114: I wasn’t aware of any Justice Department kook here.

4. (US teen/campus) in specific use of sense 1, a hard worker.

1967–8

Baker et al. CUSS 149: Kook A person who studies a great deal.

5. (orig. US campus) an annoying or mistaken person.

1960		Baltimore Sun (MD) Sun. Mag. 4 Dec. 9/1: Twitter MacAfee was the smart play of Blight Area 12, but although she pounded some ground at most of the blasts with Bugsy, the kook always blew the pad with a grub.
1961		H. Ellison ‘High Dice’ in Gentleman Junkie 88: Playing poker with [...] any of the college kooks he could fish in.
1985		Tracks (Aus.) Oct. 82: Kids with surfboards are wing-gap goody-goody kooks [Moore 1993].
1998		I. Welsh Filth 287: This is where this cook conducts his fantasy world from.