Green’s Dictionary of Slang

1. (US) a large glass of beer, just less than a pint.

1893

Sun (NY) 21 Apr. 7/2: If the hoister is on intimate terms with these schooners [of beer] he familiarly calls them ‘tubs’ or ‘high hats’. Some prefer to call them ‘geesers’.

2. (US drugs) a large opium pill.

1896		S. Crane in Sun (N.Y.) 17 May in Stallman (1966) 144: The $1 smokers usually indulge in high hats, which is the term for a large pill.
1937		B. Dai Opium Addiction in Chicago.
1949		Monteleone Criminal Sl. (rev. edn).
1956		(con. 1940s) J. Resko Reprieve 182: I knew that [...] a high hat was an oversized pill.

3. a glass of whisky and soda.

1906

in Nat. Police Gaz. (NY) 8 Dec. 6: It’d take two hunnerd high hats t’ keep my tonsils from dryin’ up .

4. (orig. US, also high hatter) a member of the social élite .

1924		P. Marks Plastic Age 196: We’re a lot of low-brows pretending to be intellectual high-hats.
1939		P. Cheyney Don’t Get Me Wrong (1956) 38: She is real Spanish Señora an’ one hundred per cent high hat if you get me.
1940		N.Y. Herald Trib. 17 July 38/2: [advert] [...] high hat; cut it out; Mr. Whiskers; Swing it!; c.o.d.; Hi ya, kid!
1953		L. Durst Jives of Dr. Hepcat (1989) 10: Jumping jills and jiving cats, upstate gates and high hats can lace their boots and tighten their wigs, here’s some jive that anybody can dig.

5. an arrogant, superior person, a snob.

1927		B. Cormack Racket Act III: That special investigatin’ grand jury o’ prominent high-hats.
1930		W.R. Burnett Iron Man 268: What did he want to team up with a guy like Lewis for? Damn dressed-up high-hatter!
1930		W. Winchell On Broadway 4 Jan. [synd. col.] Runyon [...] raps Gene Tunney [...] as being one of 1929’s High-Hats. Runyon infers that Tunney’s aloofness gives him the Tunneyache.
1946		D. Stivens Courtship of Uncle Henry 70: The highhats like that line, eh?
1992		D. Pinckney High Cotton (1993) 63: The six or seven other black students looked through him, but behind his back called him a ‘high hat’ because his instructors thought well of him.

6. a slight, a snub; usu. as give someone the high hat, or put on the high hat, to put on airs.

1934		J.H. O’Hara Appointment in Samarra 92: Go ahead. Ignore me. Give me the old high hat. I don’t care.
1947		L.J. Valentine Night Stick 129: Theories [of his murder] varied: some said that Augie was killed because his gangster confreres feared he was ‘double-crossing’ them and giving the East Side the ‘high hat’.
1962		Ragen & Finston World’s Toughest Prison 803: high hat – A slight or ‘cut’.
1975		Dundes & Pagter Urban Folklore 66: President’s Secretary: [...] Gives other girls the ‘high-hat’.
1999		R.G. Barrett Wind & Monkey (2013) [ebook] ‘All I’ve got is, “The cheque’s in the mail. Mr Maxwell’s in a meeting.” And the old, high hat’.
2001		N. Barlay Hooky Gear 189: Dont give me the high hat. Its a straight fuckin Q.