Mystery meat

Mystery Meat is a disparaging term for meat products, typically ground or otherwise processed, such as burger patties, chicken nuggets, Spam, Salisbury steaks, sausages, or hot dogs, that have an unidentifiable source. Most often the term is used in reference to food served in institutional cafeterias, such as prison food or an American public school lunch.[1][2]

The term is also sometimes applied to meat products where the species from which the meat has come from is known, but the cuts of meat used are unknown. This is often the case where the cuts of meat used include offal and mechanically separated meat, or when non-meat substitutes such as textured vegetable protein are used to stretch the meat, where explicitly stating the type of meat used might diminish the perceived palatability of the product to some consumers.