Answer:
Crooked as a rainbow, and slick as a plate, Ten thousand horses can't pull it straight.
You can tumble in it, roll in it, burn it, animal eat it. Used to cover floors, still used beyond stall doors. Freshens whatever it is placed on. Absorbs whatever is poured into it.
What wears a coat in the winter and pants in the summer?
You can hold it without using your hands or your arms. What is it?
Often held but never touched. Always wet but never rusts. Often bits but seldom bit. To use it well you must have wit.
People take me on walks and I run and have fun. What am I?