Green’s Dictionary of Slang

whetting corn n.

the vagina.

1847–81		in Halliwell Dict. Archaic and Provincial Words II 927/1: wheting-corne. The bel-chos [i.e. ‘Pudendum feminae’].
1890–1904		Farmer & Henley Sl. and Its Analogues.
1980		Maledicta IV:2 (Winter) 182: Other references to function occur in [...] whetting-corne (= grindstone), grindstone, Lob’s pound (a hand quern).