Buckinger’s boot, n. — Green’s Dictionary of Slang

Buckinger’s boot n.

[proper name of Matthew Buchinger, b.1674 in Germany and known as ‘The Little man of Nuremberg’. He was only 29" tall and born limbless, see cit. 1796. He was also a master dice manipulator. For him, a boot could fit only his third leg under third adj.]

the vagina.

1790		‘Bumper Allnight. Esquire’ Honest Fellow 212: Toasts [...] Buckinger’s boot [He had neither legs nor arms].
1796		Grose Classical Dict. of the Vulgar Tongue (3rd edn) n.p.: Buckinger’s Boot. The monosyllable. Matthew Buckinger was born without hands and legs; notwithstanding which he drew coats of arms very neatly, and could write the Lord’s Prayer within the compass of a shilling; he was married to a tall handsome woman, and traversed the country, shewing himself for money.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1890–1904		Farmer & Henley Sl. and Its Analogues.
1896		Farmer Vocabula Amatoria (1966) 104: Enclume, f. The female pudendum; ‘Buckinger’s boot’.