Answer:
This is your stomach's way of letting you know you've neglected it.
What goes up when the rain comes down?
There's one in every deck of cards and in a famous movie
What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?
What has fingers and a thumb but no hand?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.