Tight underwear threatens men with a deterioration in sperm quality and potency problems - Chinese scientists have come to this conclusion. Fans of tight swimsuits and thongs are 108% more likely to have damaged sperm DNA, 18% more likely to have a reduced sperm count, 12% more likely to have a reduced number of motile sperm, and 48% more likely to have abnormal sperm shape. Erectile dysfunction and premature ejaculation are also more common among them, which results from overheating and poor ventilation.