it was like mr. world had once said to him , we are writing the future in letters of fire and mr. town thinks that jesus christ , if he does n't piss now he 'll lose a kidney , it 'll just burst , and it was like his pop had said when they were on long journeys , when town was a kid , out on the interstate , his pop would always say , `` my back teeth are afloat , '' and mr. town could hear that voice even now , that sharp yankee accent saying `` i got to take a leak soon .