Green’s Dictionary of Slang

(orig. US) absolutely, entirely, e.g. right spang in the middle.

1772		Bridges Burlesque Homer (3rd edn) 496: Sometimes a brickbat with a bump, / Came spang against his heavy rump.
c.1790		‘Luke Caffrey’s Ghost’ in Chap Book Songs 2: He squar’d up to de two Bailies, tip’d one of dem a loving squeeze [...] and a back spang in de mazzard, dat made his daylights dance to de tune of de old cow and de hay-stack.
1843		R. Carlton New Purchase I 157: Sez I, kin a feller go spang up the round of a big punkun?
1884		J. Harrison ‘Negro English’ in Anglia VII 267: To drap spang = to let fall suddenly.
1898		J.C. Harris Tales of the Home Folks 18: [I’ll] run right spang over you with my big gray.
1908		L.W. Payne Jr ‘Word-List From East Alabama’ in DN III:iv 326: kerspang, kerspank, adv. Intensive forms of spang, spank.
1910		N.Y. Eve. Post 21 July n.p.: If one thirsts for pulque, let him follow his nose, and it will bring him right spang up against the bar.
1913		H. Kephart Our Southern Highlanders (1922) 78: I lit spang in the mud.
1922		(con. late 19C) A. Gonzales Black Border 26: Fus’ t’ing you know, ’e gone spang to de top uh ’e house.
1927		C. Woofter ‘Dialect Words and Phrases from West-Central West Virginia’ in AS II:8 365: The rock hit him spang in the eye.
1943		R.L. Bellem ‘Feature Snatch!’ Dan Turner - Hollywood Detective Feb. 🌐 I lamped the whole thing because it took place spang in front of me.
1949		Wodehouse Mating Season 108: The sudden impact plumb spang in the middle of spring, of a girl like Corky.
1955		‘Blackie’ Audett Rap Sheet 36: Them suitcases hit spang into it, one on top of the other.
1964		A. Hine Unsinkable Molly Brown 63: We had us a fight and he walked out on me. Right spang after the weddin’.
1978		D. DeLillo Running Dog (1992) 185: Got hit spang in the mouth with a pebble.