Let's smile

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 she smiled I realised I'd passed it on to him.

I thought about that smile then I realised 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!