Gravipee
Gravipee: The action of sitting for hours without the slightest sensation of having to urinate, but once you stand up you instantly get the sudden urge that you have about six seconds to get to the bathroom before you pee yourself. Gravity+pee=Gravipee
I sat and played my guitar for two hours and once I stood up gravipee hit me and I barely made it to the bathroom in time to not pee all over myself.