Green’s Dictionary of Slang

1. eccentric, foolish; esp. in daffy about, daffy on, madly in love with; also as adv.

1852		C.L. Canfield Diary of a Forty-Niner (1906) 191: Jack has gone daffy.
[1884		R. Lawson Upton-on-Severn Words 14: Daffy, simple, soft ].
1895		E. Townsend Chimmie Fadden Explains 49: Say, de whole house is daffey, only cept Miss Fannie and me. [Ibid.] 121: From his Whiskers t’ de Duchess dey is all bicycle daffy.
1905		H. Green Actors’ Boarding House (1906) 82: Them Johnny Bulls are daffy over it.
1906		S. Ford Shorty McCabe 186: A sure-enough live one, like Sadie [...] gettin’ daffy about any such overstuffed frankfurter as this specimen.
1906		Truth (Brisbane) 14 Oct. 7/3: There are men to-day who are BRILLIANT ON ONE SUBJECT, and what tho user of slang would term ‘daffy’ on another.
1912		Bisbee Dly Rev. (AZ) 23 Jan. 8/2: [advt] Decidely Dictionary Daffy. Bisbee has apparently gone ‘dictionary daffy’ [...] to secure copies of the beautiful $4.00 Webster’s New Illustrated Dictionary.
1912		H.G. van Campen ‘Our Theatrical Boarding House’ in L.A. Herald 10 Dec. 10/5: ‘You talk daffy’.
1915		S. Ford Shorty McCabe on the Job 24: That picture collection is what he’s daffy over.
1916		‘A-No. 1’ Snare of the Road 74: De white folks Ah just done tole yu about, hab gwine ’most daffy in der heads.
1926		Ethel Waters ‘Sugar’ 🎵 I get my taffy from sugar! / What’s more, I’m daffy ’bout sugar, / That sugar baby of mine!
1938		D. Runyon ‘Social Error’ in Runyon on Broadway (1954) 448: I do not blame Handsome Jack Maddigan for going daffy about her.
1943		H.A. Smith Life in a Putty Knife Factory (1948) 43: We were a daffy bunch.
1952		W. Winchell ‘On Broadway’ 2 Sept. [synd. col.] The girls at the boards here are going daffy.
1965		H.S. Thompson letter 18 Apr. in Proud Highway (1997) 507: I may be sick and a bit daffy, but something in me rebels at the idea of 500 or 5000 negroes [...] singing ‘I Love State Troopers in My Heart’.
1975		L. Rosten Dear ‘Herm’ 333: Her name is Daphne Hunziger and she is more daffy than Daphne.
1988		D. Woodrell Muscle for the Wing 8: A daffy man who oddly relished the orderliness of military jargon.
1999		Observer 13 June 15: That daffy grin that in the Sixties meant ‘Hey, look at me, aren’t I cool, I’m smoking a spliff!’.
2004		E. Weiner Drop Dead, My Lovely (2005) 49: Give this daffy frail the gate.
2011		NY Times 6 Dec. 🌐 The main character was Daisy Gamble, a daffy young woman.
2023		R. Milward Man-Eating Typewriter 4: My name will be on the oyster levers of every daffy jittery civvy.

2. (US) extremely keen.

1910

B. Fisher Mutt & Jeff 8 Oct. [synd. strip] Mutt Is Simply Daffy to Join a Fraternity at Harvard.

3. (US) mad with rage.

1910

B. Fisher Mutt & Jeff 21 Nov. [synd. strip] Jeff will be daffy when he hears I was in a box [i.e. at a horse show].

4. (Polari) drunk [but note daffy n.¹ (1)].

2019

P. Baker Fabulosa 291/1: daffy drunken.