Sample midstream. Never supply pee that is from the start of the stream. Instead, pee a bit into the toilet to get the stream going, and then pee into the cup when the stream is almost finished. The last bit of pee supposedly contains fewer metabolites than the pee at the beginning. This can help when trying to pass a drug test. It is important to pee before taking the test, as well. The first pee of the day will contain more metabolites, making it harder to pass the test. Drink a lot of water upon waking and then pee a few times before heading to the doctor.
