The feelings of euphoria and awe after playing or hearing music. Also to describe the goosebumps that accompany the listener while hearing or playing music.
As I was playing Rachmaninoff's Prelude in C Sharp Minor, I was overwhelmed by Gratiphonia.
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.