Answer:
What can be swallowed, But can also swallow you?
Round as an apple, deep as a cup, and all the kings' horses can't fill it up. What is it?
A harvest sown and reaped on the same day in an unplowed field. Which increases without growing, remains whole though it is eaten within and without. Is useless and yet the staple of nations.
I am cracked by Indiana Jones. What am I?
What is it that you must give before you can keep it.
You use it between your head and your toes, the more it works the thinner it grows.