Smiling is infectious

Smiling is infectious; you catch it like the flu,
When someone smiled at me today I started smiling too.

I passed around the corner and someone saw my grin,
When he smiled I realized I'd passed it on to him.

I thought about that smile, and realized its worth:
A single smile, just like mine, could travel round the Earth.

So if you feel a smile begin, don't leave it undetected…
Let's start an epidemic quick and get the world infected!!