In the 70's when I was a PO, most common cheat was clean urine in a balloon hidden in underware, so specimin is warm. Most PO's won't watch you give specimin that closely, but some do, so don't count on that ruse 'til you know your PO. If you can afford it, buy a hometest kit at your local drugstore (big 5 rec drugs is about $30, cheaper on the web) and take it to see where you are. The documentation with the test tells you how fast various drugs clear the system and about false positives. The most common strategies for beating the test are to flush yourself for a couple days with some herbal tea (Goldenseal?) and then take a large dose of OTC creatine a couple hours before the test. This may no longer be true, but lab equipment was usually calibrated against creatine level in the urine, so large amounts of creatine would cause equipment to calibrate too high and be "insensitive" to other illegal metabolite levels. Labs usually figure out most of these work-arounds and change their methodology with in a few months.