some of the guys that i work with use these bags that have a little tube and some kinda heater in the bag. must work i know at least 3 times dudes have used them and passed. i dont even know if it is real piss, but it works i guess. i dont have the nuts to try something like that. i get random tested but if i crash i have to take one from the coast gaurd. i like my job so i just dont do anything