Answer:
The more of them you take, the more you leave behind. What are they?
Turn us on our backs and open up our stomachs you will be the wisest of men though at start a lummox.
What is often returned, but never borrowed/
I have five letters and people eat me. When you remove my first letter I become a crime. Remove my first two letters and I am an animal. If you remove my first and last letters I'm a form of music
Many have heard it, but nobody has ever seen it. It will not speak until spoken to. What is it?
You use it between your head and your toes, the more it works the thinner it grows.