Green’s Dictionary of Slang

1. the buttocks.

1659		Mercurius Democritus 24-31 May 25: Commencing many Strange Wonders Out of [...] The Antipodes, Maggy-land, Tenebris, Fary-land, Green-land, and other adjacent Countries.
1660		Man in the Moon 2 1 Oct. 15: [He] unveiled the Conney-berry [...] and spying the way to the Antipodes as open as his intent was urgent, yet dangerous by reason of a Water-mill, which he passed through.
1660		Mercurius Fumigosus 4 28 Mar. 26: Ladyes of pleasure [...] intending to go a Frostbiting, were [...] set on by some Stout Hectors, who seized on them as their Prisoners, and Plundered them of both Clothes and Monies; ... after this they unvaled these Ladyes, of their pure fine Sailes not onely by taking up but clear off those pure white Curtains which covered the Antipodes.
1838		‘Paul Pry’ Oddities of London Life I 131: When I asked Mrs. Barr to pay for the winder, she told me to kiss the little boy’s—head’s antipodes!
1890–1904		Farmer & Henley Sl. and Its Analogues.

2. the vagina.

1659		Mercurius Democritus 31 May-7 June 37: This Simple-P— to shew his ability in Marital Discipline for the defence of Lady Venus [...] entred by force of Arms into the Antipodes of his Maid, where find the Sally-ports open, he adventured an engagement, but so drunk that little execution [...] was done.
1661		Mercurius Democritus 22 May 1: Of Maids that did their Dames beguile, / their Masters for to please / Who merrily did Sport awhile / in the Antipodes.
1832		Egan Bk of Sports 157: That tender part of poor Lalla’s person, which I should blush to mention, but which George Coleman [...] denominates ‘The head’s Antipodes’.