Cracking knuckles

To my shame, I must admit, I love doing this even in public. And people usually stare at me. Its not only embarrassing but highly annoying. How did I know that? I heard other people cracking knuckles in public. And some of them even brag about being able to make noises with their figures. One of my friends recently confessed that he use to love cracking knuckles twice every hour. When he got to high school his teachers would throw his angry looks and once a girl turned around and told him that it sounds nasty.