Green’s Dictionary of Slang

1. (orig. US) to intrude, to interfere.

1905		F. Hutchison Philosophy of Johnny the Gent 6: Just give him a chance to horn his way in, an spread a little conversation, an’ he'll make himself a one to ten chance.
1909		Van Loan ‘The Golden Ball of the Argonauts’ in Big League (2004) 73: I ain’t got no right hornin’ in here, but [etc.].
1916		J. Lait ‘Omaha Slim’ in Beef, Iron and Wine (1917) 128: They’ll vote in some guy without a chin, who’s got one foot in Wall Street an’ the other in the grave, an’ he’ll horn in the White House.
1920		Ade Hand-made Fables 307: Any small-sized Gillie can horn his way into a Chamber of Commerce or enlist as a Booster.
1930		E. Glyn Flirt & Flapper 8: The petting party I horned in on last night left me limp.
1932		(con. 1910s) J.T. Farrell Young Lonigan in Studs Lonigan (1936) 63: He wished he could horn in on one of those parties.
1941		B. Schulberg What Makes Sammy Run? (1992) 21: You can’t horn in on this, it’s our birthday party.
1951		D. Stivens Jimmy Brockett 111: You said you were only forming a company to show pictures and now you’re horning in on the distribution.
1953		‘John Eagle’ Hoodlums (2021) 124: Phony as the made-up broads in the movies [...] When you tie up with them everyone’s trying to horn in.
1954		Wodehouse Jeeves and the Feudal Spirit 194: Spode horned in again.
1962		(con. 1953–7) L. Yablonsky Violent Gang (1967) 93: If someone comes by their territory or block or candy store, and tries to horn in on it, they’ll fight.
1970		G.F. Newman Sir, You Bastard 87: Johnny Doleman hadn’t come hustling or trying to horn in.
1982		P. Theroux London Embassy 41: He figured the other guy [...] suspected him of trying to horn in on the family fortune.
1991		B. McCarthy Vice Cop 188: ‘[T]he investigation had really grown. [...] Even the feds were trying to horn in’.
2001		‘Randy Everhard’ Tattoo of a Naked Lady 48: Fully inflated, I horned in on the girl-girl act.

2. (US) to procure admission for a third party.

1920

A. Baer Writing Football 10 Nov. [synd. col.] He had horned them all in on free passes.

1. to eject.

1850		in Calif. Hist. Society Quarterly VIII (1929) 268: Sutter is wanting to horn out some squatters off what he calls his property which they deny & say they squat on the Government land [DA].
1881		Phila. Times 5 June n.p.: There are others who believe that MacVeagh is trying his best to horn Blaine out of the Cabinet herd [DA].
1912		C. Mathewson Pitching in a Pitch 52: ‘He’s tryin’ to horn my friend Bill out of a job,’ I’ve heard catchers charge against a youngster.

2. (US) to escape.

1919

Van Loan ‘The National Commission Decides’ in Score by Innings (2004) 294: They [i.e. mice] horned out of the box where Fowler kept ’em.