There are many ways to celebrate national cheeseburger day! The best way is to gather your friends and family together and start up the grill. Nothing brings people together like a delicious cheeseburger! Some places will even be handing pout special offers. Burger 21, a fast-casual restaurant chain will be celebrating national cheeseburger day by rewarding its guests with a cheesy burger after they download its new mobile app and loyalty rewards program. Burger 21 currents has 17 locations spread throughout Florida, Arizona, New York, California, and Virginia.