My dad bought a home drug test. It's a piss test, it can't test for saliva or hair. I tested positive for weed, but got out of trouble because I got him to believe that I was with a kid who was smoking a joint. But I'm getting tested again. How can I pass it? I'm 15, so I can't order any chemicals online or go to a headshop to get anything made to dilute it. Can I just put some tap water in my piss? What about vinegar?