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. 

One year later, the same guy hears a knock 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 at him and says in a tiny voice,
"What the heck was that all about?"