Burger KingMustard on your Whopper instead of MayoMustardWhopperSimply ask for Mustard on your Whopper instead of Mayo. Or you can get both!All Locations4 - Medium$1.29 Whopper Jr.$3.49 WhopperMustard - No additional costhttp://hackthemenu.com/burger-king/secret-menu/mustard-whopper/Everyone knows that the Whopper is the flagship burger at Burger King. So what twist could be put on the Whopper, you ask? Well, how about you try ordering a Mustard Whopper off the BK Secret Menu? It is the classic Whopper, but the mayonaisse is replaced with a flavor punch of mustard. It is a simple twist, but it really changes the whole Whopper. So why not give this Mustard Whopper from the Burger King secret menu the chance that it deserves, and go get yourself one today! Be sure to check out the Burger King Secret Menu as well as visiting our home page to check out the complete list of All the Secret Menus from all your favorite restaurants!