Silly Question
Ulrich Blau is professor of logic in Munich. For the last 30 years or so he's been working on an enormous book in which he solves all known and several unknown problems in logic, foundations of mathematics, and philosophy in general. If you ever come across that book (it's not published yet), I'd strongly recommend you just skip the non-technical introduction (and conclusion). It's really getting much better where the formulas begin. Anyway, in the introductory chapter I found a silly question that I once discovered myself when I still went to school:
Does this question have an answer?
(In Blau's version, it goes "Can you answer the question you are now reading either affirmatively or negatively?")