system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we get an urge to crack our bones?

I have found myself getting the urge to crack my knees, lower back, knuckles, etc. at various times in the day. Why is that? What implications can this have in the future?
gpt
You aren't actually cracking your bones. You are just popping air bubbles between them. The urge to crack your bones comes from a slight pain relief and an appeasing sound( similar to the urge to pop bubbles in bubble wrap)