The key to stuffing, as in so many things, is practice. Accomplished rectal stuffers, many of whom can be found in our prison system, work both to expand their rectal capacity and, at least as importantly, to train their bodies to suppress the urge to defecate. I spoke to Dr. William Whitehead of the University of North Carolina, an expert on the movements of the gastrointestinal system, who says, "There are a lot of circumstances in which people develop a much larger rectum, or a megarectum." A megarectum is just a large rectum, generally defined as having a capacity of more than 1,500 mL, and Dr. Whitehead is used to seeing it from those with severe constipation. "Through repeated retention of stool the rectum becomes enlarged," he says, but when I asked if manual effort--practice, basically--could also enlarge the capacity, he said "I think it could."