Spanish for tripe, meat or parts of, very tough-to-digest, first or second stomach or other digestive elements of ruminating animals. The dish consists of tripe, boiled until tender and flavored with the classic Spanish ingredients like onions, garlic, and tomatoes.
Callos is also popular in the Philippines, being inherited from the Spanish during the World War II. It is often considered to be the "poor man's food" because this is very inexpensive. It composed of the stomach lining of a cow.