about 17 days ago — Italy I like it I hate it Via awesome 9 3 Are You saw in the previous post? How's that for a good timing Don't miss the next one! Dr. Donald Unger was one of the most dedicated men ever. He cracked his knuckles in only his left hand to prove that it wasn’t bad. He did this for 60 years and was able to prove that cracking your knuckles would not harm you.