ALBERTA, CANADA – Knuckle-cracking; you either love it or hate it! But now some crafty Canucks are claiming they’ve cracked the case of why joints pop, and you’re going to want to hear their explanation. For many years, researchers couldn’t quite put their fingers on it. What is actually making that cracking sound? But recently at the University of Alberta, something clicked. The Canadians put down their maple syrup, they fired up an MRI machine and shot video of someone taking a crack at it.