A guy hears a knocking on his door.  He opens it up, and no
one is there.  He looks all around and he finally sees a
little snail sitting on the doormat.  He picks it up and
throws it across the street into a field.

Ten years go by, and one day he hears a knocking on his
door.  He opens it up and no one is there.

He looks all around, and he finally sees a little snail
sitting on the doormat.

The snail looks up and says, "What the hell was that all
about?"