Chitterlings are the intestines of beef, calf, and pig, with the latter being the most popular. They are not commonly consumed today, except in rural areas, but are often used in processed meat products. Before being sold, chitterlings are cleaned and boiled to remove any unpleasant odor. If they have not been pre-boiled, they should be washed thoroughly and simmered for 2 to 3 hours until tender.