Green’s Dictionary of Slang

1. a bugle or trumpet.

1848		Morn. Post 11 Dec. 6/1: Specimen of the Taylor Songster to be intrduced into the Rough and Ready Clubs:- Sound the hewgag, strike the tonjon.
1855		Knickerbocker (NY) Dec. 617: Strike the hewgag! sound the tomjohn! Let the loud hosanna ring!
1862		W.W. Heartsill diary Fourteen Hundred and Ninety One Days in the Confederate Army (1992) 10 Nov. 223: The ‘Hu-gag’ (as Briggs calls the Bugle) has sounded and we are off west.
1863		Nashville Daily Union (TN) 15 May 2/3: Let the hew-gag be sounded in mournful cadence.
1877		Examiner 13 Oct. 6/5: Confound their hewgags.
1881		Louisiana Capitolian (Baton Rouge, LA) 12 Mar. 2/2: Haven! Where is the Capitolian, that it does not sound the hewgag.
1890		Princeton Union (Minn.) 13 Nov. 1/6: In New York it is Tammany’s turn to bur red fire and sound the hewgag.
1902		Imperial Press & Farmer (San Diego, CA) 1 Feb. 7/2: Oh, sound the ringing hewgag and lift high the brimming ‘pony!’.
1906		Army and Navy Life Oct. 498: The bugle has been changed in the midshipmen’s vocabulary to the gugag [HDAS].
1908		Imperial Press & Farmer (San Diego, CA) 25 Jan. 5/1: It was reported with a great flourish of trumpets and sounding of hewgags.
1915		True Democrat (Bayou Sara, LA) 6 Nov. 1/3: A great sounding of hewgags and beating of tom-toms is going on.
1949		Pacific Hist. Rev. 18 67: When the Hewgag blew, the brethren gathered from far and near. It was a signal that a sucker had appeared in camp.

2. (US campus) something for which one has no specific name.

1871		L.H. Bagg Four Years at Yale 45: Hewgag, a what-d’ye-call-it, a thingumbob.
1894		N.Y. Eve. World 23 Nov. 8/4: [headline] All Tremble at the ‘Hewgag’ Hasbrouck Heights Doesn‘t Know What It Is, but Thinks It’s Something Awful.
1922		Mt Sterling Advocate (KY) 6 Apr. 3/2: I couldn’t play a dew-dad that a feller has to pick... But they allers hears my hew-gag when I welt her with a stick.

3. a battle cry [f. sense 1].

1977

R. Coover Public Burning (1979) 446: Deeds, not words: that was Ike’s hewgag.