Saw this on a Facebook post. Happened to my son when he was just walking but kept picking up one foot. Took his shoe off and started to take his sock off. It wouldn't let loose and he screamed. After that I checked his socks and other threads that would come loose. Even brand new socks and booties. That was in the 70s. It became a habit with me, my sisters and also my sons did the same thing. They turned the sock inside out to check for loose threads. Hurts as bad as having a torn toenail get caught in a piece of carpet thread and your own socks.