[openknot]

The recruits believe it's a treatment for a lung condition where you cough up blood during training.

From the NYTimes article: "Many men were coughing up bloody fluid from a condition called swimming-induced pulmonary edema — a potentially life-threatening ailment that is so common among men training in the frigid water at BUD/S that SEALs refer to it casually by the acronym SIPE.

"[...] Seaman Mullen showed up for his second attempt at BUD/S in January with fresh determination and a used car. But by the end of the second week, he was spitting up bloody fluid and struggling to breathe.

"“I said, go to the hospital right away,” his mother recalled. “He said, ‘No, ma, if you want to go to the hospital, they will make you quit first. Besides, it’s just SIPE.’”

"Ms. Mullen said her son, on the advice of other SEAL candidates, started secretly taking the erectile dysfunction drug Viagra, which was against Navy rules but used by SEALs as a potential treatment for SIPE. He recovered enough to keep training.""