I always have more fun trying to answer the increasingly-non-sequitur "why"s (in increasing complexity) than they have asking them.

“Why is the sky blue?”

“Because the air is blue!”

“Why?”

“Because air molecules are so small that they get in the way of the blue light and bounce it around.”

“Why?”

“Because the other colors are big enough to get through.”

“Why?”

“Because the things we see as ‘colors’ are just different wavelengths of light.”

“Why?”

“Because it was evolutionarily advantageous for us to be able to distinguish between different objects by the wavelengths of light that they reflect.”

“Why?”

“Partially because things that reflect some wavelengths are dangerous to eat, and others are healthy to eat, and we wouldn’t know the difference based on the luminosity alone.”

“Why?”

“Presumably because ripening and decomposing food doesn’t undergo a visible physical change until long after it’s already unsafe, but it changes color very quickly.”

“Why?”

“Hmm. I think because the chemical processes that cause color changes and the chemical processes that accompany the growth of microorganisms tend to happen together.”

They always tap out from boredom long before I do, and it’s fun trying to figure out the super esoteric stuff. Besides, the "why"s are so unspecific that you can answer it for any part of the question.