...make the #4)? I am 17 and I have had this problem as long as I can remember, everyone I show is weirded out by it and no one can explain what it is. When I tuck my thumb into my palm (like you do when you make the #4) it causes my fingers to curl, once in that position my fingers are stuck, I can bend them further, but cannot straighten them. The only way to regain movement is to move my thumb away from my hand. it is not particularly annoying (unless I have to show the number four with my hand), I am not looking for a cure, just an explanation.