crack their knuckles

[rao007]

could someone please tell me what does it mean "when someone cracks their knuckles"
Thank you
Rao007

 

[Ouisch]

It can be done a variety of ways, but picture someone interlacing all their fingers. Now they take their hands and point their palms away from their body, and bend all their fingers slightly backwards in the process. Their knuckles will make a series of popping sounds as they do this. This is commonly referred to as "cracking your knuckles."

 

[Batfink]

It means that a person is in preparation to do something very important.