To those who don't...you have no idea how good it feels. I suspect that the gases that are in the fluid continue to buid up. That's what they do to get in there in the first place. Those who crack their knuckles feel a sense of pressure to do so and when the bubbles pop and the gas is released, so is the pressure. So it does in fact feel good to those who do it. Just because it diesn't feel good to you, doesn't mean you should decide for anybody else except yourself. In other words you should have no opinion. I'm 60 years old, I have been cracking my knuckles since as early as I can possibly remember with no signs of anything being out of normal with my hands. In fact my wife says my hands are exceptinally strong as she can tell from frequent short massages.