A Gimlet . . . or other such cocktail . . . if you drink too many your head hurts like the dickens.
What the devil is a Dickens??
I thought it had something to do with the famous author. I just didn’t know what the relation was. You might be surprised that the phrase has nothing to do with Charles Dickens, as I assumed it did. And, since there isn’t any correlation that explains that!

Along the same vein, dickens is very much like deuce . . . as in What the deuce?! . . . deuce is another old English name for the Devil.
So, there you have it . . .