Someone's going to get benched next practice lol.
Ok, so for people saying that energy supplements is psychological...yes that is true, but it is not the only thing that is affected. Obviously an over consumption of simple sugars, and electrolytes will change the amount of times our nerve cells fire off...this will affect hormone release as well. So if you THINK it's not working, your body is still being affected by it, and there's no exception to that. However, if you THINK IT IS working than it's going to affect your performance twice as much, whether its good or bad.
What would happen if you had to go really badly, but you were next in performance? Maybe you couldn't go and you have to have full expressions and full energy for your performance with possibility of stunts with the extreme urge to go to the restroom. Formula for problems!
Usually, you will never have to go as soon as you touch the stage. Your parasympathetic system temporarily is turned off because its responsible for resting, digesting and defecating. Your sympathetic system is on overload, that's why your heart races, you feel out of breath even before anything starts and you get cotton mouth. Your digestive system shut down and any and all fluids you have in your system are used for running all processes. You know why your BP goes up? B/C vasopressin and ADH hormones release to prevent urine secretion, via a "renin-angiotensin-aldosterone" system. The more fluid you have, the more pressure you accumulate, the higher your blood pressure is. Your body won't release the fluid when your amped up, b/c your spincter muscles are closed.
So yes, drink water before hand, but not too much, b/c you will get this problem, and the only way to solve this problem is to pee it out. But regardless, when its game time, you get ready to lock and load, and you won't think about having to go.