@solderandchaos I like stuff like questions like a play on words: "what's brown and sticky?" or "what's red and wiry?"

"What is heavier a gramme of water or wood?", "Why do you play pooh-sticks with a stick not a nail?", "Why does a compass point north?", or even "What is a compass?"

"Where is the centre of Britain?", "How far is it to the sea?" or "What is faster a European or North African swallow?"

I guess I am too much of a dad/physicist to be good at this.

@solderandchaos there is also the controversial "How many planets are there in the solar system?", "How would you cut the sun in half?", "Why is the sky blue?", "How far is outer space?", "What is zero multiplied by infinity?"...or added or even multiplied by...

There are things like "How do I know what you have told me is true?", "What is the sound of one hand clapping?", "What is between being and not?", "When should I remain silent?" or "If a lion could speak would we understand them?"

@solderandchaos I guess blue skies are too easy to find but as a physicist I would insist that the answer makes a clear reference to Rayleigh scattering and a bonus for the wavelength power law...

@solderandchaos Douglas Adams was really good at sprinkling his work with this profound stuff