Green’s Dictionary of Slang

1. (orig. US) to talk loudly or foolishly, to nag; thus yawping n. and adj.

1836		T. Haliburton Clockmaker (1843) I 269: They stand starin and yawpin, all eyes and mouth.
1882		Nat. Police Gaz. (NY) 29 Apr. 2/1: Ell Perkins, yawping and yawling over the country again.
1898		Dly Teleg. 30 Dec. 8/6: ‘The way they yawped out little lullabies about [...] the dear old ’ome was enought to break your ’eart’.
1901		Sydney Sportsman (Surry Hills, NSW) 6 Feb. 2/7: They go yawpin’ ’round tellin’ how ’tain’t Christian to get money that way.
1903		A. Binstead Pitcher in Paradise 52: The orgie [...] is continued indefinitely by the yawping of ballads.
1928		M. Bodenheim Georgie May 28: Uh-huh, still yawping.
1930		(con. 1910s) L. Nason A Corporal Once 13: A phonograph yawped.
1941		K. Tennant Battlers 39: What do you s’pose those eminent old coves were yawping about?
1962		R. Cook Crust on its Uppers 188: The judge’s crusty remarks for everyone to yawp over in the linens.
1975		(con. 1900s) G. Swarthout Shootist 7: At the corner of Chihuahua and Overland a newsboy yawped.
1983		R. Price Breaks 292: ‘C’mon, sweetheart, it ain’t gonna get any greener,’ Fonseca yawped out his window.

2. to vomit.

1948

(con. 1944) N. Mailer Naked and Dead 517: Wilson yawped onto the grass. The odor was faintly unpleasant.