My two-year-old baby brother started this thing when he was about ten months old. His poop has always been firm and pretty big. It is nothing to catch him lying on his belly in the middle of the floor with a big bulging poop on his butt. When he is poopy, he will grab himself between the legs and hump. Now keep in mind that his poop is only on his butt and nowhere near the front of his diaper, though sometimes he does enjoy a hard hot tennisball-sized poop against his perineum (the skin between the anus and the genital region, for people who don't know what that is called.) We don't know why, but my brother has started referring to his poop as "gur," and whenever he is poopy, he will tell us that he is gurry. So we have taken to calling it gur. He likes the feel of his poop for some reason and he seems to get very excited when he does his humping thing on the floor. Why does he do it, and will this hurt him?