Green’s Dictionary of Slang

1. drunk.

1708		Humours of a Coffee-House 9 Jan. 86: Well, Mr. Guzzle, I find you are got in for’t.
1726		Proceedings Old Bailey 11 July 3/2: The Deceas’d was very drunk and Sarah Davis was Pretty well in for it, and they two fell a Quarreling.
1737		B. Franklin ‘Drinkers Dictionary’ in Pennsylvania Gazette 6 Jan. in AS XII:2 91: They come to be well understood to signify plainly that A MAN IS DRUNK. [...] Well in for’t.
1770		Gent.’s Mag. 559: To express the condition of an Honest Fellow, and no Flincher, under the Effects of good Fellowship, it is said that he is [...] In for it.
1802		N.Y. Gazette and General Advertiser 28 July 3/1: On Monday morning last, some of the Seamen belonging to the Essex frigate, paraded the streets, a little in for’t, singing the new song about the Good Ship constitution.
1804		C.L. Lewes Comic Sketches 26: While others would say he had, ‘Bung’d his eye — Was knocked up — How came ye so — Had got his little hat on — Top-Heavy — Pot- Valiant — That he had been in the sun — That he was in for it’.
1822		Tom And Jerry; Musical Extravaganza 54: In for it, bosky.
1839		Crim.-Con. Gaz. 9 Feb. 43/3: elements of fuddling 1. Comfortable. 2 Merry. 3. Noisy. 4. Tipsy. 5. Fairly in for’t. 6. Done up. 7. Amorous. 8. Knock’d down. 9. Knock’d up. 10. Finish’d.

2. willing, committed to, eager.

1821		R. Waln Hermit in America on Visit to Phila. 2nd series 23: ‘I warrant the bang-ups have crooked their elbows’ quoth Tom [...] ‘all been in for a dinner party.’.
1845		J. Lindridge Sixteen-String Jack 173: Here, my hearty, we are in for a booze.
1848		Boston Blade 10 June n.p.: It was no use, and seeing that he was ‘in for it,’ he stammered out that it ‘suited to a T’.
1854		G.J. Whyte-Melville General Bounce 343: They are in for it now, and both gather confidence.
1908		‘Old Sleuth’ Dock Rats of N.Y. (2006) 115: The fellow had a wicked eye. He saw that he had run into a snap, and he was determined to take a desperate chance to get out of it. ‘I’m in for it,’ he remarked.
1926		Wood & Goddard Dict. Amer. Sl.
1932		(con. 1917–19) Dos Passos Nineteen Nineteen in USA (1966) 494: Don’t want you fellers to know what I’m in for.
1941		K. Tennant Battlers 207: We ain’t no bed of roses, me an’ Jimmy, but, I guess, Stray, you know what you’re in for.
1952		Lait & Mortimer USA Confidential 162: Cowboys in for a toot.
1963		A.S. Fleischman Venetian Blonde (2006) 147: The jawsmith turned to a stoned drunk. ‘You in for a buck?’.

3. pregnant.

1923

J. Manchon Le Slang.