the.com/knuckles
the body's built-in percussion section, cracking out a symphony nobody asked for
crack sourcePopping nitrogen bubbles in joint fluid, not bones
no arthritisDecades of cracking shown harmless in studies
refractory periodCan't crack again for about 20 minutes
white-knuckleFear drains blood from gripping fingers
sega iconA red echidna borrowed the name in 1994