Popular topping is a term used to describe the most commonly used toppings for pizzas. Pepperoni, meatballs, and MUSHROOMS are all popular toppings that are often used on pizzas. Pepperoni is a type of Italian-American cured sausage made from pork and beef, while meatballs are a type of ground meat formed into small balls and cooked in sauce. MUSHROOMS are a type of fungus that can be cooked and added to pizzas as a topping. All three of these toppings are popular choices for pizza lovers.