Green’s Dictionary of Slang

what the dickens! excl.

a euph. for what the devil! excl.

1600		T. Heywood Edward IV (1874) I 40: What the dickens? is it loue that makes ye prate to me so fondly?
1730		J. Gay Wife of Bath (rev. edn) V iii: Whatadickens, asleep!
1802		G. Colman Yngr Poor Gentleman I i: What a dickens! be that son Stephen keeping such a clatter?
1877		Worcs. Chron. 13 Oct. 3/1: Ahem! what the dickens!
1961		‘Frank Richards’ Billy Bunter at Butlins 213: What the dickens —.
1999		Guardian G2 30 July 3: Other projects in the pipeline: [...] What the Dickens? (quiz show).