Green’s Dictionary of Slang

a general interrogatory intensifier; a var. on what the devil...? phr.

1549		T. Chaloner (trans.) Erasmus Praise of Folie (1509) 90: Whiche [statement] maketh the hearer, meruailyng at the estrangenesse of the deuise oftentymes to muttre to him selfe, now whither the diuell wilt thou.
1697		Female Wits III i: Where the devil are these blockheads?
1806		J. Gillray More Pigs than Teats 5 March (cartoon): Where the devil do they think I shall find Wash and Grains for all their Guts?
1814		T. Dibdin Ninth Statue II iii: Where the devil’s the learned doctor now, to teach me the way?
1838		Dickens Oliver Twist (1966) 242: Where the devil have you been?
1887		G. Devol Forty Years a Gambler 39: Look here, my boy, where in the d[evi]l were you raised?
1901		E.W. Hornung Black Mask (1992) 164: Where the devil are you driving us?
1910		H.G. Wells Hist. of Mr Polly (1946) 200: Where the devil do I come in?
1920		‘Sapper’ Bulldog Drummond 181: Then where the devil does Potts come in?
1945		G. Fairlie Capt. Bulldog Drummond 156: Where the devil was Hugh Drummond?
1982		G.V. Higgins Patriot Game (1985) 21: What I wanted to know was why I was awake in some bed I’d never seen before, and where the devil the bed was.