Might be another option too. Get some clean urine from a friend, put it in a clean smallish squeeze bottle, and hang that inside your pants so that the tip of it is around your zipper area. Because it's against your groin, the temps should be okay. Then squeeze it out. It sounds almost exactly like you *are* pissing. The only drawback is when you stop squeezing and air bubbles back into the bottle, makes a little abnormal sound. But if he's outside the room, well, that just makes it easy as pie.