As part of Burger King’s 70th birthday celebrations, and to mark today’s grand holiday- National Hamburger Day- get a free hamburger with any 70c purchase. This deal is available via the app and bk.com for order ahead, dine-in, or with the 6-digit “My Code” (where available) located in your account, or via delivery, at participating U.S. restaurants. That’s a savings of $2 and a tasty treat.