Answer:
The man who invented it doesn't want it. The man who bought it doesn't need it. The man who needs it doesn't know it. What is it?
Round as a button, deep as a well. If you want me to talk, you must first pull my tail.
I have legs but walk not, a strong back but work not. Two good arms but reach not. A seat but sit and tarry not.
Just head and foot yet never tires of dancing.
By the way, what never moves, wears shoes, sandals and boots, but has no feet?
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?