Green’s Dictionary of Slang

1. the vagina.

1680

M. Stevenson Wits Paraphras’d 78: And think you such a senseless Lubbard / Can prize the Treasure of your Cup-board.

2. the stomach; thus v. cupboard, to digest.

1832		Satirist (London) 5 Aug. 250/4: ‘I’ll give it you where you cupboard your grub, blessed if I don’t, and no mistake’.
1842		Spirit of the Times (N.Y.) 5 Nov. 421: Bell buttons [...] marked the graceful outward sweep of his ‘cupboard.’.