Sept. 18 is National Cheeseburger Day, and restaurants are celebrating the food holiday with discounts and free burgers. According to Ranker, a crowd-sourced voting platform, the top five fast-food burgers were: Five Guys Bacon Cheeseburger, Five Guys Hamburger, In-N-Out Double Double, Five Guys Cheeseburger and Culver’s ButterBurger. Burgers at Whataburger, Wendy's, Steak 'n Shake, Burger King, McDonald's and Red Robin also make the top 20 list. McDonald's is offering double cheeseburgers for 50 cents with a mobile app deal Saturday. Get a free cheeseburger at Burger King with a $1 or more purchase and an offer on the BK app. Wendy’s has a buy-one-get-one free premium cheeseburger deal on its app, which includes the new Big Bacon Cheddar Cheeseburger. To be on the safe side, always check with your closest location before heading out as the offers are only available at participating locations. 📷: Leigh Beisch, McDonald's #nationalcheeseburgerday