milking pail, n. — Green’s Dictionary of Slang

milking pail n.

[note double entendre in D’Urfey, Pills to Purge Melancholy (1719): ‘What Joys are found, / In Russet Gown, / Young, plump and round, / And sweet and sound, / That carry the Milking Pail’]

the vagina.

1724		A. Ramsay Tea-table Misc. (1733) IV 412: You girls of Venus game [...] If men were so wise to value the prize Of the wares most fit for sale, What store of beaux would daub their clothes, To save a nose, by following those Who carry the milking-pail?
1890–1904		Farmer & Henley Sl. and Its Analogues.
1896		Farmer Vocabula Amatoria (1966) 242: Seau, m. The female pudendum; ‘the milking-pail’.