Why do we dance and hop when we desperately need to go number 1?

What is the reason for all the movement when we really need to go pee? Is it a subconscious reaction to distract the mind from a full bladder, or does sloshing the pee around in your bladder make it somehow better? I would assume not, since that probably increases the physical urge that you need to go pee, but why then do we dance and hop...