Answer:
So cold damp and dark I am. To stay you would refrain yet those who occupy me do never complain.
You use me between your head and your toes the more I work the thinner I grow.
I am an animal and a hair product
I am gentle enough to soothe your skin light enough to fly in the sky and strong enough to crack rocks.
What jumps when it walks, but sits when it stands?
I flow from the Homerβs mouth when he sees doughnuts.