It's definitely addicting. I've found that once I know I can crack a knuckle I keep cracking it. I didn't used to crack the last (distal) knuckle on my fingers

It's definitely addicting. I've found that once I know I can crack a knuckle I keep cracking it. I didn't used to crack the last (distal) knuckle on my fingers and I remember one time in high school a friend of mine grabbed my hand in class and cracked it. The first time it really hurt but ever since then I crack all those knuckles as part of my "routine".