The bones don't have to be broken though. Cracking your knuckles is also an example of crepitus. As is that crackling sound your knees sometimes make when you stand up after squatting.
Aaah, so it was the crepitus from my fibula that I could hear/feel as I vainly tried to run the injury off. Thanks, I thought the graunching sound was something else entirely.
Ah so that's the noise I get from my knees when I stand up too!
Also the noise from the w*nker in the library seat next to me for the last hour who has ben cracking his knuckles, getting up and down time after time and pushing past my seat.
Has anybody ever got into a pagga in a library out there?