"Mac Coin" commemorates Big Mac 50th anniversary

Photo courtesy of @MCDonalds
Photo courtesy of @MCDonalds

The Big Mac is turning 50, and McDonald's plans to celebrate in a major way. The chain will be handing out limited edition "Mac Coins" on Thursday with the purchase of a Big Mac.

More than six billion coins will be handed out worldwide. Starting Aug. 3, customers can cash in the currency for a free Big Mac.

The coins will be handed out  on a first-come first served basis. The deal runs through the rest of 2018.

There are five collectible designs, one for each decade of the burger's existence. 

More than a billion Big Macs were sold last year alone.