Green’s Dictionary of Slang

1. to lay down or stake money, esp. to put up bail; thus post the cole; post the neddies; post the pony; post the tin.

1789		G. Parker Life’s Painter 143: Shew me the person that when the neddies are posted, or pinched hard, that won’t snitch, from high treason, Lutterlough, down to a gallows lumper.
1796		Grose Classical Dict. of the Vulgar Tongue (3rd edn) n.p.: Post the poney; lay down the money.
1812		Vaux Vocab. of the Flash Lang. in McLachlan (1964) 259: post, or post the poney To stake, or law down the money, as on laying a bet, or concluding a bargain.
1820		Jack Randall’s Diary 69: To all who tip the blunt, or post the ready.
1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc. 138: ‘Post the Poney,’ or ‘post down the cole,’ put down the money.
1824		J. Wight Mornings in Bow St. 273: The gentleman to whom the heavy belonged, now swore that Mr. Jonas Tunks shouldpost the bluntt for it that is to say, he should pay for it.
1833		H. Smith Gale Middleton 1 150: When shall we finger the blunt? [...] Are you sure of your pal? Will he come to the mark, — Will he post the pony?
1837		Roscommon Jrnl 16 Sept. 2/1: The applicant posted the necessary.
1845		‘Knyghte and the Taylzeour’s Daughter’ in Martin & Aytoun Bon Gaultier Ballads 8: Vainly do you ask for tick [...] my rum ’un, I expect you’ll post the tin.
1859		Matsell Vocabulum 69: post Pay; put up. post the cole Pay the money.
1864, 1867, 1870		Hotten Sl. Dict. 204: POST, to pay down; ‘post the pony’ signifies to place the stakes played for on the table.
1865		Leaves from Diary of Celebrated Burglar 91/1: I then drew up an agreement assigning all that was in the ‘crib’ to Jack [...] and he ‘posted the cole’ agreed upon, on the table.
1873		Sl. Dict. 124: Coin ‘to post the coin’ ― sometimes ‘post the coal’ ― a sporting phrase meaning to make a deposit of money for a match of any.
1882		Sydney Sl. Dict. (2 edn) 7: Post - To pay down the stakes or deposit. To ‘post the pony,’ to put the stakes on the table.
1885		Daily Tel. 7 Sept. n.p.: He must to-day post the final deposit [F&H].
1891		Licensed Victuallers’ Gazette 3 Apr. n.p.: Done! Post the money [F&H].
1895		C. Crowe Aus. Sl. Dict. 60: Post, to pay;‘post the pony’; to place the stakes on the table [...] Post the Cole, pay the money.

2. (UK Und.) to swear on oath.

1822

Life and Trial of James Mackcoull 299: She believed he had ne’er a loge; and was sure, unless he rapp’d, he could not post it that the tatler nim’d was his’ne.