Letra de Smile for you

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 then I 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!