Green’s Dictionary of Slang

exchequer n.

the vagina.

a.1680		Rochester ‘A Satire which the King took out of his Pocket’ in Works of Rochester (1721) 21: Now thy Exchequer is remov’d to France; / T’ enrich a Harlot all made up of French, / Not worthy to be call’d a Whore, but Wench? / C---d indeed deserves that noble Name, / Whose monst’rous Letch’ry exceeds all Fame.
1890–1904		Farmer & Henley Sl. and Its Analogues.