Anyone can get diarrhea. In fact, the typical American adult experiences diarrhea about four times a year, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Most cases of diarrhea, defined as loose, watery stools occurring more than three times in one day, last a day or two and need no treatment. Find out more about this common digestive problem by taking this quiz, based on information from the NIDDK and the American Academy of Pediatrics.