I've had to take pre-employment and random piss tests for 20 years, and fortunately, it's never been a problem for me. On the occasion when I didn't know in advance, I usually just ask for some water to drink until things are ready to flow...Hell, if they want to watch, (which sometimes they do) fine with me...just stand back so you don't get splashed...

I've been on several jobs, where a vial of clean urine is worth $50...always someone willing to pay, and someone willing to take their money...THAT'S why they want to watch you piss...the temperature thing is fairly easy to beat, but not when they're standing right there...