Anyway, all was well until he felt a sharp pain in his penis. Naturally he rushed himself to a clinic where an eel was extracted from his bladder.
While the truth of this story cannot be confirmed, there are medical reports of critters crawling or swimming up the human urethra and finding their way into the bladder.
In India, for instance, doctors found a leech that had wriggled its way into the bladder of a 16-year-old boy. Apparently the leech entered while the boy was partially submerged in a rice paddy. After suffering with unexplained fevers and the feeling of urgently having to urinate for two months, the boy was taken to the doctors who eventually had to operate to remove the creature.