Answer:
When we stand up it lies flat. When we lie back it stands up.
You give it to your daddy, you give to your mommy, you give it to your sister and your brother and even give it to Fido and Lassie. If they give it back to you, then you both have one. You also have an unlimited supply. What is it?
What has a spine, tail, and leash but isn't a dog?
A girl was ten on her last birthday, and will be twelve on her next birthday. How is this possible?
What is yours but only used by others?
Born in the ocean and white as snow. When I fall back to water I disappear without a trace.