Dictionary of the Vulgar Tongue: 1811 slang dictionary

The 1811 Dictionary of the Vulgar Tongue is a reprint of "the Lexicon balatronicum; a dictionary of buckish slang, university wit, and pickpocket eloquence (and now considerably altered and enlarged, with the modern changes and improvements, by a member of the whip club.)" It is available in full for free on Project Gutenberg, and it's mind-croggling, with definitions like:
CHOAK PEAR. Figuratively, an unanswerable objection: also a machine formerly used in Holland by robbers; it was of iron, shaped like a pear; this they forced into the mouths of persons from whom they intended to extort money; and on turning a key, certain interior springs thrust forth a number of points, in all directions, which so enlarged it, that it could not be taken out of the mouth: and the iron, being case-hardened, could not be filed: the only methods of getting rid of it, were either by cutting the mouth, or advertizing a reward for the key, These pears were also called pears of agony.
Link (Thanks, Kip!)

Update: David reports that Smartfilter, the censorware jerks who block Boing Boing also target this ebook as "pornography."