Score 50-cent double cheeseburgers at McDonald's on Monday

Monday is National Cheeseburger Day, and to celebrate, McDonald's has a promotion for fans of the Golden Arches to snag a deal on double cheeseburgers.

Sure, most of us use mobile wallets these days anyway, but for just two quarters, five dimes or ten nickels, you can score a double cheeseburger at McDonald's on Sept. 18 only. However, you must order on the McDonald's app to take advantage of the deal.

Plus, if you're new to downloading the McDonald's app and rewards program, customers who make a $1 minimum purchase (excluding tax) will get a free Big Mac.

The offer is only valid one time through the last day of the month, and for first-time app users at participating McDonald's only.