It’s a line made famous by a certain Mad Milliner in a novel about a little girls trip to Wonderland. What’s the answer? Well, read a little further and you’ll get this,

“Have you guessed the riddle yet?” the Hatter said, turning to Alice again.
“No, I give it up,” Alice replied. “What’s the answer?”
“I haven’t the slightest idea,” said the Hatter.

Not satisfied? Louis Carrol won’t be much help either,

Enquiries have been so often addressed to me, as to whether any answer to the Hatter’s Riddle can be imagined, that I may as well put on record here what seems to me to be a fairly appropriate answer, viz: ‘Because it can produce a few notes, tho they are very flat; and it is nevar put with the wrong end in front!’ This, however, is merely an afterthought; the Riddle, as originally invented, had no answer at all.

- Louis Carrol, Alice in Wonderland, Preface

. . . or maybe he is.

I think Mr. Carrol inadvertently pointed out a lesson, one that all of us would do well to remember — sometimes the right answer, the only real answer is that there isn’t a right answer and the correct thing to do is to smile, discontinue beating your head against the wall and move onto the next question.