the whizzinator is the best.. i know the gov. was trying to shut them down though.. they have something similar also that uses "clean" pee that isn't yours. my buddy had one (whizzinator) and pissed in front of his po weekly and never got screwed.. nice for him cuz he smoked about 1 oz a week lol..
ya, this also works if you overdose on it.. get all sunburned looking and itchy. also, from my xp, using niacin made my pee too clean and i had to re-pee the next day. most places now just treat it as a fail if the p is "too clean".
If they dont watch you a glue bottle full of clean piss and some hand warmers to keep the temps up works. a condom full in your under wear will also keep the temps up and a sharp object will empty the piss balloon in a second.
Drink TONS of water the day of at least two hours before. Drink as much as you can constantly. You'll start to pee in an hour and continue to have to pee quite often. Continue to drink water (but not so much as to make yourself sick). After the first 3 or 4 pisses your piss won't have enough time to absorb more THC from your fat cells so you'll piss pretty clean the more you piss before the test. I've done that and was pissing every 10 minutes. But I passed.