Green’s Dictionary of Slang

low countries n.

1. the anus.

1592

Shakespeare Henry VI Pt 2 II ii: The rest of thy low-countries have made a shift to eat up thy holland.

2. the female genitals.

1594		Gesta Grayorum (1688) 66: To conclude, they burn all those Vessels that transport any dry Wares into the Low-Countries.
1602		Middleton Blurt, Master Constable B: The commodities which are sent out of the Low Countries, (and put in vessels called Mother Cornelius’s dry-fats) are most common in France!
1607		Dekker & Webster Northward Hoe II i: A Dutch Merchant, that would spill all he’s been able to make ith’ low countries, but to take measure of my Holland sheetes when I lye in ’em.
c.1616		W. Goddard Satir Y-Call Dialogue [title page] Imprinted in the Low countryes for all such gentlewomen as are not altogeather Idle nor yet well ocvpyed.
1630		J. Taylor ‘Sculler’ in Works (1869) III 24: Lieutenant Puffe from Cleaueland is return’d, / Where entering of a breach was sorely burn’d: / And from reuenge hee’l neuer be perswaded, / Till the low Countries he hath quite inuaded.
1650		H. Nevile Newes from the New Exchange 19: [A] Lady of an old low-country Colonell [...] who hath run through most of the Regiment [...] Since her coming to England, she hath traded never a jot the lesse in the low-countries.
1656		‘The Threading of the Needle’ in Sportive Wit in Bold (1979) 157: O that I durst but shoot a gulf I know, / Or in the Lower Countries my seed sow.
1660		Wandring Whore II 8: I would never have ventured in her hot Low-country, though she would have payd me for the drudgery.
1702		T. Brown Letters from the Dead to the Living in Works (1760) II 202: It is not fit th silent beard should know how much it has been abus’d by the other parts of the body, for if it did it would [...] make it open its sluice to the drowning of the low countries in an inundation of salt-water.
1787		Harris’s List of Covent-Garden Ladies 55: Flow’ry mountains, / Mossy fountains, / Shady woods, / Christal floods [...] When Addison wrote these lines, he little thought he was describiong Mrs Cl—l—nd’s low countries.
1890–1904		Farmer & Henley Sl. and Its Analogues.

SE in slang uses

In phrases

Low Country soldier (n.) [the characteristics of those who have soldiered in the Low Countries or of Dutch troops]

a good drinking companion.

1650

Eighth Liberal Science n.p.: The titles which they – the drinkers – give one to another [...] A Low-Country Soldier.