The term 'Burger Joint Supply' can be broken down into two crossword solutions: BUNS (4 letters). BUNS are a type of bread roll that is often used as the base for hamburgers. They are usually round and flat, and can be made from a variety of ingredients such as wheat, rye, or even potato flour. BUNS are an essential part of any burger joint's supply, as they provide the foundation for the burgers they serve.