Happy birthday, Big Mac

The Big Mac, one of McDonald’s most iconic menu items, is enjoying its 50th anniversary this year.

To celebrate, McDonald’s is launching MacCoin.

The collectible currency will be available Thursday, beginning with lunchtime service. It allows customers to buy a Big Mac and get another one free.

More than 6.2 million MacCoins will be distributed at McDonald’s restaurants around the world while supplies last. Customers receive a MacCoin with the purchase of a Big Mac.

And, starting Friday and lasting through 2018, they can redeem their MacCoin for a free Big Mac.

The commemorative coins feature five designs, each representing a different decade of the Big Mac.

The Big Mac was invented in 1967 by Jim Delligatti, a McDonald’s owner and operator from Pittsburgh. The burger debuted on McDonald’s national menu in 1968.

“When my great-grandfather Jim Delligatti invented the Big Mac at his grill in Uniontown, Pennsylvania, he just wanted to make his local customers happy,” Nick Delligatti, fourth-generation McDonald’s owner and operator and great-grandson the inventor of the Big Mac, said in a news release. “August 2 would have been my great-grandfather’s 100th birthday, and I believe he would be very proud knowing his humble sandwich has made such a lasting impression that people all around the world can enjoy it wherever they find a McDonald’s.”

For more information, visit www.mcdonalds.com.