Assuming OP weighs at least 150lbs, it would take more than 120 cans of red bull to actaully kill you. I can assume you would start seeing medical problems around 50-70, but its not like you stomach can take that much anyways, and you would be having medical problems related to so much liquid intake long before the sugar/caffeine actually kills you. The same could be said about water. Average stomachs can hold around 2 liters of stuff.
So no, 8 cans wont to shit except make you jittery and hyper.