ummm...about the "not-being-able-to-crack-for-15-min"thing, i can crack both of my thumbs like 10 times in a row, then if i stop crack the other, i can come back and crack the first another 10 times and the cycle repeats. Btw for bloodhound about the learning the neck/back thing. I strongley suggest not doing it. Since i've found out that i could crack them, my neck and back hurt so damn much! Also you wont be able to stop cracking them easily and i've heard that cracking the neck/spine could lead to unwanted problems. Btw whats the verdict? Is hand cracking bad for you? There seems to be evidence going both ways so im kinda stuck in the middle and wondering what's your verdict?