Green’s Dictionary of Slang

cuckoo adj.

also coo-coo, cookoo, cuckoo’s nest, koo koo
[cuckoo n.1 (2)]

crazy, eccentric, insane.

Cobbett’s Wkly 1 Sept. 19/2: One of the turncoat fellows [...] had [...] the effrontery to prefer against me the cuckoo charge of inconsistency!
[US]‘Hugh McHugh’ Skidoo! 98: In presenting these Cuckoo Recipes for the Chafing Dish to his friends [etc.].
[US]A. Baer Two and Three 25 Jan. [synd. col.] Makes a speech while eating shad. That proves he’s coo-coo.
[US]O.O. McIntyre New York Day by Day 16 Sept. [synd. col.] That German bullet is making me go off my nut, lady. I’m about cuckoo.
[UK]C. Hume Cruel Fellowship 281: I must have been coo-coo.
[US] (ref. to 1898) N. Kimball Amer. Madam (1981) 264: The most brutal kookoo johns with crazy ideas.
[US]J. Lait Gangster Girl 158: This is some kind o’ cookoo gink.
[US]Blanche Calloway ‘Concentratin’ on You’ [lyrics] Seems that I’m goin’ coo-coo, / Dizzy as I can be.
[US]N. Davis ‘Kansas City Flash’ in Ruhm Hard-Boiled Detective (1977) 89: She must be coo-coo.
[US]L. Dent ‘Angelfish’ in Goulart (1967) 245: She does cuckoo things, and I wouldn’t want her around as a fixture.
[US]J.T. Farrell ‘Street Scene’ in To Whom It May Concern 72: Another bum cooked on canned heat. He’s gone coo-coo.
[US]H. Miller Sexus (1969) 36: I was for straight gibberish. One should go cuckoo!
[UK]A. Buckeridge Jennings’ Diary 16: He’s as cuckoo as a coot, if you ask me.
[US](con. 1940s) G. Mandel Wax Boom 50: It’s that cuckoo kid Atman.
[US]G. & K. Swarthout Whichaway (1967) 39: The old gent was mad as a hatter. They all were, he understood — this cuckoo, vanishing breed.
[US]‘Iceberg Slim’ Mama Black Widow 20: Not ha ha funny but koo koo funny.
[US](con. 1916) G. Swarthout Tin Lizzie Troop (1978) 49: Yoor cuckoo for me, goddammit.
[NZ]P. Wilson N.Z. Jack 120: Like my old man [...] He’s cuckoo beyond recall.
[US]J. Ellroy Brown’s Requiem 234: Cathcart’s cuckoo on the subject.
[UK]Observer Rev. 10 Oct. 5: I was still intubated, and the tubes were driving me cuckoo.
[UK](con. 1981) A. Wheatle East of Acre Lane 228: De Beast would go fucking cuckoo’s nest.
[US]N. Green Angel of Montague Street (2004) 161: Mentally unfit [...] coo-coo.

In phrases

knock cuckoo (v.) (also knock coo-coo, slap cuckoo)(US)

1. to knock out, lit. and fig.

A. Baer Flapping over new Leaves 4 Jan. [synd. col.] It rides away and then rides back and knocks them coo-coo.
[US]H.C. Witwer Fighting Blood 292: One paper even said that the beating I had took from Gunner Slade before I slapped him double cuckoo had ruined me for life.
[US]B. Cormack Racket Act III: I’ll knock your whole Organization cuckoo!
[US]R.E. Howard ‘Pit of the Serpent’ Fight Stories July [Internet] ‘I’ve seen ’em knocked even more cuckoo,’ said the dip.
[UK]R. Westerby Wide Boys Never Work (1938) 197: Knocked all the others cuckoo.
[US](con. 1930s) R. Wright Lawd Today 169: He marries a girl, goes into the ring the same day, and knocks a guy coocoo!

2. to amaze, to astonish.

[US](con. 1920s) J.T. Farrell Young Manhood in Studs Lonigan (1936) 219: He’d go back to the pool room, and tell the lads what a lay he had [...] and knock them cuckoo. [Ibid.] 244: Dressed that way, tackling so hard he’d knock them cuckoo.