Is it bad to crack your knuckles?
The Real Answer
Cracking your knuckles has not been shown to cause hand arthritis. The familiar pop is associated with rapid separation of the joint surfaces and formation of a gas cavity in the synovial fluid — a process called tribonucleation — rather than a pre-existing bubble simply collapsing. For most people, ordinary painless knuckle cracking is not considered harmful. But if cracking is painful, causes swelling, follows an injury, or a joint repeatedly catches or feels unstable, that is a different situation and is worth medical evaluation.
You're allowed to make that noise with your body and it does nothing, which means you've spent decades getting yelled at for a completely victimless crime. Your joints are just waving at you. The sound offends people more than actual damage ever could.
The Dunce Dynamics Institute Examines Why People Ask This
This is usually asked right after someone's parent or teacher told them to stop doing it, creating a doubt that lasts into adulthood. The myth is so entrenched that even people who've looked it up still feel slightly guilty every time they do it — which means they're going to keep doing it and keep feeling guilty, forever.