Green’s Dictionary of Slang

the vagina; the vulva.

1604		Wit of a Woman v 432: These dauncers, sometimes do teach them trickes, aboue trenchmore, yea & sometimes such la voltas, that they mount so high, that you may see their hey nony, nony, nony no.
1611		Florio Queen Anna’s New World of Words n.p.: Fossa ... a womans pleasure-pit, nony-nony, or pallace of pleasure.
1619		Fletcher Humorous Lieutenant IV iv: Was that brave Heart made to pant for a placket: And now i’th’ dog-days too, when nothing dare love! That noble Mind to melt away and moulder For a hey nonny, nonny!
c.1660		‘Downe sate the shepherd’ in Furnivall & Hales Bishop Percy’s Folio Manuscript of Loose and Humorous Songs (1868) 58: [She has] hayre as blacke as any croe [...] all downe along to her hynononino.
1890–1904		Farmer & Henley Sl. and Its Analogues.