Boneless pork rectums or pork bungs are used in dry sausages, smoked sausage and liverwurst. Bungs can also be used as imitation calamari because, despite the differences in origin, they both share a basic rubbery texture. However, as of 2015 there is no evidence that they are actually being served in this manner.
Pork rectums are the ends of the large intestine terminating at the anus. In order to prepare them as food, a manufacturer first cuts the rectum free from the setting and washes it thoroughly. The bung then goes through a sliming and inflating process. Sliming is a process in which rollers squeeze the rectum in order to remove the mucous membrane.
Finally, the rectum is salted and graded for use. Most bungs are 3 to 5 feet long and 1 to 2 inches across. They are also sewn together and used as casings. Cow, sheep and goat bungs are also used in food and for stuffing.
A pork rectum isn't the only part of the animal's intestines used in food preparation. The stomach, small intestine, large intestine and bladder also serve particular purposes. For instance, the pig's stomach is ground and used in sausage as well as stuffing head cheeses.