Revolving Smiles

One day I awoke with a smile upon my face and so went on my way. I passed by one who's response was a smile and as I saw him pass another their response was a smile. I realized that I had passed my smile onto him, whom passed it onto another, now I know that my smile shall devolve and around the world it shall travel. If just one smile revolves, just imagin what many will do?.... So come on and let's smile. We'll start an epidemic!