‘What the Dickens?’ may be an everyday expression where English is the predominant language, but it poses all sorts of problems for the non-English speaker.
The form is better known as an idiom – defined in my dictionary as:
Idiom – a peculiar mode of expression, colloquial speech.
Idioms are a minefield for advanced students of the English language
The first volume of the dictionary of idioms was put together by two University lecturers and a school teacher who had begun to list all those commonly used phrases in their family circle.
The first volume concentrated on a verb plus a proposition – such as ‘write up’ or ‘put down’.
The second volume was twice as long and included more modern phrases – Nice one Cyril (Cyril Knowles, left back for Tottenham Hotspur which became the supporters anthem), ‘sick as a parrot’ and possibly ‘over the moon’, opening Pandora’s box, grist to the mill, ‘opening the floodgates’ but ‘closing the stable door’; all of which leads to a rib-tickling, mind boggling discussion.
These and many, many more are included in The Oxford Dictionary of Current Idiomatic English.