Was a slogan made from USA in the 1930s,when diner’ hunger was often bigger than their budget. The deal with such restaurants is an unlimited amount of food, usually arranged as a self-service buffet and usually of pretty low quality, for a fixed price. It could be simple known as people pay a fixed fee and can then help themselves to have as much food as they want to eat in a restaurant or hotels. Normally this is self-service.