Answer:
Often found in doctor's offices and pirate flags
Tomorrow's yesterday. Yesterday's tomorrow. What is it?
You can tumble in it, Roll in it, Burn it, Animals eat it, Used to cover floors, Still used beyond stall doors. Freshens whatever it is placed on, Absorbs whatever is poured into it. What is it?
Small, containing light, You'll need it in the dark, It will provide that spark, and shine into the night. Will light up any pyre, 'Cause it can help make a fire.
You can do this with your friends. You can do this with your nose. But don't do it with your friend's nose!
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?