Today Is National Pizza Day WASHINGTON (dpa-AFX) - It s again that day of the year when we celebrate a fast food that is one of the most popular among children and adults equally. Tuesday is the National Pizza Day in the U.S. when major food and beverage outlets across the nation promote pizzas with irresistible deals for pizza lovers. An interesting fact still doing the rounds is that Pizza s generally circular in shape and eaten in triangles, but comes packed in a square box. Pizzas, which are essentially flatbreads with tasty sauce, toppings and cheese, were initially known to be a food for the commons which was easy on the pockets.