1) cranberry juice is a diuretic and as such just removes water from your body, does not burn fat and remove THC, don't bother with it. people say it works because they are just diluting they're piss with it. Also don't bother with the headshop drinks.
2) exercise a ton. especially high intensity stuff, like liners and sprints. I mean to point of puking. If you play a sport , remember hellweek, ya do that...pluss some.
3) eat like a bird and what you do eat make it protein.
4) niacin. it dialates small blood vessels which run throughout your tissue. the theory here is that it allows for easier transport of the thc from your fat, because the passagways are dialated.
5) 24 hours before test: IMPORTANT: EAt like a fucking horse anything and everything. you don't want to be burning any fat at this point, because that will release thc into your system. Drink like a camel, you want to dilute your piss. Take B-vitamins, it will make your piss turn yellow instead of clear. Start loading Creatine like 3 days before, labs test this to make sure you are not diluting your piss. piss midstream. You can still get caught if the specific gravity of the piss is off, sorry no help there.
Seriously this is the only thing you can do if you actually plan on using your own piss.
Better options:
THe Whizzinator
http://www.ureasample.com/buy-drug-test-solutions/store/whizzinator.htm
More options are having someones piss in a big visine bottle, or smaller turkey baster.
Bottom line is it all depends on how fat you are and how much you smoke, not how often.
BIG difference"