I passed a drug test i had to do in a medical office in 2 days all i did was drank 6 litters of water the night before and pumped vitamin b suppliments to turn my pee yellow (makes it more neon not such yellow fyi) drank probably another litter of water before the test. Home tests are just as easy to pass because you shouldn't need to make ur pee yellow from the b suppliments (unless ur parents know u can water down the results). you could probably smoke up to 3 days before you're test and still pass if you knew it was comming.