I'm sure you've heard as a child, "Don't crack your knuckles because it could give you arthritis as an adult". Well, this is a completely busted myth. Yes it is bad for your joints, but as a child it shouldn't cause any problems. Your toe, finger joints, and your elbow rest in a synovial fluids. When bending your fingers or toes, these fluids tend to bubble and burst. That is why you hear the so called "Cracking sound". If you have a really bad habit, and continue to do this as an adult, it can break down the tissues and fluids that protect your joints and eventually develop osteoarthritis. But this is very very rare.
