Green’s Dictionary of Slang

1. (UK und.) a fighting cock.

1784

H. Lemoine ‘The Clever Fellow’ in Wit’s Mag. 155/1: I’ll race my Jack, or bait a bull, / Or fight my doodle-doo.

2. the vagina or penis, i.e. thing n. (2) [ext. doodle n.² (1)].

1834		‘The Maiden’s Surprise’ in Libertine’s Songster in Spedding & Watt (eds) I 130: She rush’d to his arms with lecherous haste / [...] / In and out, round about, doodle doo.
a.1969		‘London Town’ in G. Logsdon Whorehouse Bells Were Ringing (1995) 242: As I walked out on London’s street, / A pretty maid I chanced to meet. / She offered me gold and silver, too, / Just to crawl right onto her doodle-doo. / ‘Your doodle-do and what is that?’ / ‘It’s something like old granny’s cap; / It’s fringed all around and split in two, / And that’s what I call my doodle-doo.’ [...] You left your father and mother, too, / And followed dad for his doodle-doo.

3. (US, also doodly-do) nothing at all, e.g. I can’t do doodle-do about it [the trad. phonetic version of the cock’s crowing, cock-a-doodle-do].

1969		J. Broughton Thud Ridge 100: If you tell the stupid bomb that the wind is going to be 10 knots and that is why you are releasing him pointed toward a place short of his target, the bomb can’t do doodle-doo, about it.
1979		(con. WWII) W.P. McGivern Soldiers of ’44 367: That don’t make a doodly-do bit of difference.