Green’s Dictionary of Slang

used in a variety of mild oaths; a euph. for Jesus! excl.

1837		R.M. Bird Nick of the Woods I 61: No, by Jehosaphat!
1844		Central Jrnl (Kosciusko, MS) 6 Aug. 1/2: ‘By Jehosaphat,’ says I, ‘if — ’ ‘No swearing,’ says the squire.
1851		M. Reid Scalp-Hunters III 181: Geehosaphat! hyers a feller ridin’ ’ithout eyther saddle or bridle!
1853		Life in Boston & N.Y. (Boston, MA) 1 Oct. n.p.: Prescott, of the Times, said he could write — oh, Jehosiphat! but he couldn’t make a speech.
1858		G.W. Harris ‘Sut Lovingood’s Adventures in New York’ N.Y. Atlas XXI Aug. in Inge (1967) 138: Jehosefat! how he mizzled t’uther way.
1861		Kentish Chron. 4 May 4/2: Crack! went both pistols at me [...] ‘Missed by Geehosaphat!’ cried a fellow.
1865		H. Kingsley Hillyars and Burtons (1870) 131: Mr. Nalder frightened her [...] with his way of prefacing half his remarks by saying ‘Je-hoshaphat.’.
1873		W.H. Thomes Bushrangers 187: ‘By Jehossephat! what is that?’ Hopeful asked.
1879		Sheffield Indep. 5 Sept. 2/4: He looked up and said, ‘Great Jehoshaphat! what a jump’.
1882		Bristol Magpie 21 Sept. 6/2: But O, jehosaphat! talk about public spirit!
1883		Sweet & Knox On a Mexican Mustang, Through Texas 246: Geehossifat! I’m the Long-range Rover of the Sierra Mojada Mountains.
1885		Bulletin (Sydney) 8 Aug. 22/4: [S]he said, ‘This, sir, is my husband!’ As one stricken dead, Stanley could only exclaim, ‘Jehoshaphat!’.
1890		Bird o’ Freedom 15 Jan. 1/3: ‘Jehosophat!’ put in a bystander. ‘How you must have shrunk!’.
1900		Marvel XIV:363 Oct. 8: With a muttered ‘Jehosophat!’ he ducked to cover again.
1904		Sydney Sportsman (Surry Hills, NSW) 27 Jan. 3/4: Geewhiz, and likewise Geewhitaker, Jehoram, Jehosaphat!
1904		Kansas Agitator (Garnett, KS) 4 Mar. 3/4: Great jehosiphat! Who ever heard of ribbons with bones before!
1908		L.W. Payne Jr ‘Word-List From East Alabama’ in DN III:iv 324: Jehosaphat Jenkins, interj.
1925		S. Lewis Arrowsmith 266: Great Jehoshaphat, can’t you even sew on buttons?
1944		J.M. Inks diary Eight Bailed Out (1954) 19 Sept. 69: Holy Jehosophat!
1986		O. Senior ‘Ballad’ Summer Lightning 112: Well Jehosiphat! I never see or hear such a thing.