Answer:
What can you always count on?
How can a pants pocket be empty, but still have something in it?
Devils, unicorns and goats all share this feature.
I run over fields and woods all day. Under the bed at night I sit not alone. My tongue hangs out, up and to the rear, awaiting to be filled in the morning
What happens to an egg every time you look at it?
What never gets any wetter no matter how hard it rains?