Answer:
You can't keep this until you have given it. What is it?
Mouth up it gets filled, mouth down it gets empty.
My second is performed by my first, and it is thought a thief by the marks of my whole might be caught.
What goes up and down without moving?
What goes inside boots and outside shoes?
you hold my tail while I fish for you
Easy
Animal
Difficult
Food
Funny
Kids
Logic
What am I?