Green’s Dictionary of Slang

1. the vagina [‘because frequently felt’ (Grose, 1796)].

c.1698		B.E. Dict. Canting Crew n.p.: Top-diver a Lover of Women. An old Top-diver, one that has Lov’d Old-hat in his time.
1703		Levellers: A Dial. concerning Matrimony in Harleian Misc. V (1810) 451: My dear sister, be cautious in this point [...] let no old fornicator be an assessor, commissioner, or collector of your duty: he has, in his time loved a bit of old hat.
1723		C. Walker Authentick Memoirs of Sally Salisbury 103: If the Pedantick Blockhead should come, he should only have a little bit of Old-Hat to stay his Stomach, till he got some Harlot of his own Purtanical Flock, for his Money.
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. c.1698].
1743		Fielding Life of Jonathan Wild (1784) II 176: [footnote] The term Old Hat, is at present used by the vulgar in no very honourable sense.
1759–67		Sterne Tristram Shandy (1996) 255: A chapter of chambermaids, green-gowns, and old hats.
1785		Grose Classical Dict. of the Vulgar Tongue Hat, old hat, a woman’s privities.
1798		‘Zodiac’ in Hilaria 117: Whose nose is eternally smelling old hat, / And who mounts ev’ry cow that he meets.
1812		J. Bell Jr. (ed.) Rhymes of Northern Bards 254: Each cuddles his coney or rabbit, / And pleasantly purrs with puss-cats; / Hence with husky harlots cohabit, / And handle a herdling’s old hats.
1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc.
1826		Pierce Egan’s Life in London 21 May 547/1: The Captain was a fam’d crack shot, and ere he left for Erin, / The Old Hats pigeon-shooting corps, as private did appear in.
1833		‘The Blowing’s Catalogue’ in Funny Songster in Spedding & Watt (eds) Bawdy Songbooks (2011) III 45: For slashing size and lip so bold, / And old hat so black with hair / It is Poll’s pride.
1841		in Gentleman’s Spicey Songster [song title] Mother H’s Knocking Shop; or, A Bit Of Old Hat!
1842		Wkly Rake (NY) 9 July n.p.: ‘Don’t you like to see your wife dressed well?’ asked the cunning milliner. ‘Yes, but I am paticularly fond of old hat’.
1843		N.Y. Sporting Whip 25 Feb. 1/2: The depression in the various branches of female trade has driven many amorous girls to the pave, they thinking, previous to embracing the damnable vocation, that it is a charming life, full of fun, pleasure, and devoid of all trouble. But this BARGAINING FOR OLD HAT isn’t what it is cracked up to be, which they learn to their disagreeable disappointment after a trial.
c.1850		Peeping Tom (London) 18 69: [cartoon caption] The Wife, concealing her Paramour in the closet, who is leaving his new hat [...] in exchange for the old hat he had been enjoying before the Husband disturbed them.
1861		N.E. Police Gaz. (Boston, MA) 12 Oct. 5/1: Two girls from No. 9 Tyler court were making a very conspicuous display of their jockey hats [...] ‘When this old hat was new,’ &c.
c.1864		‘The Female Auctioneer’ in Rakish Rhymer (1917) 137: And if your fond of nice— old hat, / I’ve some that you can buy.
1896		Farmer Vocabula Amatoria (1966) 41: Bonnet, m. The female pudendum; ‘the old hat’.
1900–10		Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.] 106: OLD HAT [...] a vulgar name for the female article of commerce.

2. (Aus.) sexual intercourse.

1900–10

Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.].