Bob and Bun is a popular restaurant chain in the United States. The name is derived from the two founders, Bob and Bun, who opened the first restaurant in the late 1980s. The restaurant specializes in burgers, sandwiches, and other fast food items. The DOS in the crossword solution refers to the restaurant's signature dish, the Double Original Sandwich. This sandwich consists of two beef patties, lettuce, tomato, onion, pickles, and mayonnaise on a toasted bun.