snail

Who's That Knocking at My Door? 

A man heard a faint knock on his front door, opened it, and saw a snail on his porch.

"What the heck is this?" he said, and bent down, picked up the snail,

examined it, and threw it across the street.  

Two months later, the man heard another faint knock on the front door.

He opened it, saw nothing, then looked down.

The snail on the porch said, "Hey! What was that all about?"