Answer:
It's got twists and turns, but has no curves. Twist it to fix it, turn it to ruin it. What is it?
What's black when you get it, red when you use it, and white when you're all through with it?
Upon me you can tread, though softly under cover. And I will take you places, that you have yet to discover. I'm high, and I'm low, though flat in the middle. And though a joy to the children, adults think of me little.
Just head and foot yet never tires of dancing.
If you drop me I'm sure to crack. But give me a smile and I'll always smile back.
You use it between your head and your toes, the more it works the thinner it grows.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?