Answer:
If you have it, you want to share it. If you share it, you don't have it.
I have a hundred legs, but cannot stand. I have a long neck, but no head. I cannot see. I'm neat and tidy as can be.
What five-letter word becomes shorter when you add two more letters?
A house full, a yard full, a chimney full, no one can get a spoonful.
A hill full, a hole full; yet you cannot catch a bowl full. What is it?
Walk on the living, they don't even mumble. Walk on the dead, they mutter and grumble.