WOW!
Have you never had a drug test before? For starters, no they don't make you strip naked. Everytime I've took one they made me empty my pockets before I went to the bathroom and I wasn't allowed to flush the toilet afterwards (if you have more than the cup will hold LOL). Second, they'll know if you use fake urine. For that matter , what in the hell is this fake urine made of? All in all, a very bad idea.
Better idea would be a get a friend to piss in a cup for you. Put it in a condom, tie it up, and hide it somewhere on your body where it will get and stay warm. If you bring them a cold cup of pee they'll know. Then again best thing to do would be not doing drugs when you're hunting for a job.
If all you did was smoke weed, just drink a sh*t-ton of water, starting now, to help flush it out of your system (or at least dilute it). I highly doubt the logic behind it works, but that's what everyone I know that smokes weed does. My gf's bestfriend took a drug test the other day and she had smoked two days before (they sprung the test on her last minute). She drank GALLONS of water up until the test and passed no problem (it surprised the hell out of me).
So if you intend to cheat the test, either try that method or score some pee off a clean buddy. You may fail but it's better than failing AND looking like an idiot after you try to use fake urine