Green’s Dictionary of Slang

1. the male or female genitals.

1605		Chapman & Jonson Eastward Ho! III ii: Dost remember since thou and I clapped what-d’ye-call’ts in the garret?
1646		Parliament of Women B4: That man which promises a pritty Maid a good turn, and doth not perform it within three moneths, shall loose his what do you call them.
1653		Urquhart (trans.) Rabelais III 28: [Hans Carvel’s] Middle-finger was as far as it could reach within the What-d’-ye-call-it of his Wife.
1674		Cavendish Triumphant Widow Act IV: Why you have hardly enough [clothes] left to hide, hum – your hum, what de’ call ’ems?
1694		Motteux (trans.) Rabelais IV 47: [She uncovered] her self up to the Chin ... and plainly shew’d her What de’e call them.
1772		Bridges Burlesque Homer (3rd edn) 117: I wish with both my pluck and gallum / I’d never touch’d her what-d’ye-callum, But gone where damsels in the Park / Watch to earn sixpence in the dark.
1785		‘Roger Ranger’ Covent Garden Jester 28: She told him her watch stood. I don’t wonder at that, madam, replied his highness, when it is so near to your what-do-you-call-it.
1793		Bacchanalian Mag. 111: At night at home then he would play / With her same — what d’ye call it.
1890–1904		Farmer & Henley Sl. and Its Analogues.

2. see what-d’you-call-it n.