I’ll let you read Ben Zimmer’s musings on whether this is a joke replacement of “what the dickens” or is meant as something closer to “WTF”. The comments give other examples of Greek-letter puns in Victorian poems and pamphlets too. I half want to believe that this really is the first attested appearance of “WTF” – rather like the “OMG, Churchill” story, it just really appeals to me – but I suspect the timing is no good on this one, and 1881 is just far too early for this expression. Still, an excellent puzzle based on the history of the Latin alphabet.
Fair warning: the Strong Language blog contains, well, strong language.