Green’s Dictionary of Slang

(US) a general greeting; also as v. see cit. 1989.

1874		F.C. Burnand My Time 165: ‘Well’, he said squeakily, ‘how-de-do?’.
1885		Thomas Co. Cat 10 Dec. 3/3: He could have struck a brother officer who stopped himn with a pleasant ‘Howdy’do?’.
1887		C. Chesnutt ‘The Goophered Grapevine’ The Conjure Woman (1899) 183: Hoddy do, ma’m.
1894		Truth (Sydney) 25 Feb. 2/2: How-dy-dowdy, how d’ye do?
1901		W.N. Harben Westerfelt 144: ‘Howdy’ do?’, said one, eyeing Westerfelt suspiciously.
1906		J.W. Carr ‘Words from Northwest Arkansas’ in DN III:ii 141: howdy do? interj. How do you do.
1911		Gem 7 Oct. 8: They won’t ever say ‘Howdy-do?’ to me again on Broadway.
1931		Shelby & Stoney Po’ Buckra 97: I just came on da-own to say Ha-owdy-do.
1943		L. Bennett ‘Partin’’ Jam. Humour 17: Tell pupa plenty howdy [...] Tell John howdy do!
1959		E. De Roo Young Wolves 6: ‘Howdy-do-dee,’ Pa muttered clownishly. He bowed.
1960		(con. c.1928) D. Holman-Hunt My Grandmothers and I (1987) 177: How-de-do.
1979		E. Lovelace Dragon Can’t Dance (1998) 96: I say ‘good morning’, I say ‘good evening’. I say ‘Howde do’.
1989		(con. 1960s) M. Kingston Tripmaster Monkey 57: A salesman howdy-doodied her.
1992		P. Earley Hot House 370: I’m doing some running around and howdy-doody, I get my butt busted in some fucking tiny town in Arizona.
1993		R. Doyle Paddy Clarke Ha Ha Ha 192: Howdy-doody.
2001		K. Sampson Outlaws (ms.) 20: The manager of the club [...] comes over and gives you the big howdy-doody.