lemme guess u smoked pot and drank same shit happened to a friend of mine hes like 21 now but was 20 at the time it happened he was tellin me about it and was like "ya so i tryed fuckin this bitch at a party and then i couldnt get a boner" i just looked at him n laughed then we figured out that its prolly cus the mixture of the weed and the alchohal cus another friend had the same shit happen under the same circumstances. Unless u didnt smoke pot... then id say give viagra a call hahahaha jk