What is the button on lower left inside of a polo style shirt for?

I have this button on several shirts I own. I have no idea what it is for. Can some one out there help me with this please?

FabABulous :)2009-08-07T10:58:32Z

Favorite Answer

It makes the shirt look waaaaay cooler ;)

Anonymous2009-08-07T17:54:15Z

It's a spare in case one of the buttons on your shirt comes off. You just sew the spare on in it's place.

chrono80082009-08-07T17:54:10Z

It's there in case one of the collar buttons falls off. Then you can detach the extra button and sew it on where the other one was.

TJ W2009-08-07T17:54:30Z

It's not that big of a mystery. Its so that if you lose a button at the top, you have one to replace it with.

Diablo Blanco2009-08-07T17:54:53Z

Don't unbutton it whatever you do! It holds the entire shirt together!