Green’s Dictionary of Slang

(US) a euph. for god-damned adj.

1785		M. Lonsdale Spanish Rivals I ii: bast.: Narcisso de Medici! ’Gad, the very man I want to hear of. [...] peter: Why, mun, that’s my master, and a gosh drat comical shaver it is! — Oh! it’s a comical shaver.
1893		Indiana State Sentinel (Indianapolis, IN) 30 Aug. 11/3: ‘I’ll be gosh-darned ef that ain’t the damnedest’.
1905		H. Green Actors’ Boarding House (1906) 169: I’d a been free from that De Shine [...] if it wasn’t fur the notoriety, an’ me so gosh darned sensitive!
1906		C. M’Govern Sarjint Larry an’ Frinds 68: Does I believe in spiritoolism? Not in a pair of gosh hang holy minits!
1914		C. Holme Lonely Plough (1931) 107: There’s the gosh-dangdest trouble you ever struck coming for you.
1917		Free Trade Jrnl (Ottowa, IL) 24 Nov. 6/1: ‘Goshdang it, judge’ [...] The brewery driver swore.
1927		C. Sandburg ‘Si Hubbard’ in Amer. Songbag 351: We heard that gosh-durned sharper say: ‘Four dollars, quick!’.
1931		‘Scissor Bill’ in Irwin Amer. Tramp and Und. Sl. 247: And Scissor Bill declares ‘The country must be freed / From Niggers, Japs and Dutchmen and the gosh darn Swede’.
1948		in Randolph & Legman Ozark Folksongs and Folklore (1992) I 418: Though he pushed and he pulled, and he rubbed it with lard, / The gosh darn thing just wouldn’ get hard.
1954		Mad mag. July 15: Dash-blast the gosh darned blankety heck!
1968		G. Cuomo Among Thieves 383: You should go back to your old goshdarn college.
1999		Guardian Rev. 19 Nov. 6: A David Lynch that Twin Peaks’ gosh-darnit Agent Cooper would recognise as kin.
1999		Indep. Rev. 29 Oct. 12: He never forced me to do a gosh-darn thing.
2019		N. Walker Cherry 107: ‘Cripes! Foolin around on him with a gosh-dang porch ape, son’.