Drink a huge amount of water before the test. You can also try drinking Apple Cider Vinegar, but it tastes horrible and hard to swallow (at least for me). I've smoked weed up to the day before a drug test and then just drank about a gallon of water before going in for testing, its worked for me every time. Also give them mid-stream pee, not the beginning or end. Good luck! 👍