Imagine a world in which the colors of things have changed from what we consider normal. Assume the following changes: Snow is now red.
Grass is now black.
The sky is now brown.
Blood is now white.
Soot is now green. In such a world, what is the color of dirt?

Dirt is now blue. The puzzle consists of pairs that exchange colors. Since the sky is now brown, brown things become blue. Today's brain teaser courtesy of Braingle.com.