Methamphetamines could be detectable moreso than marijuana, though.

MJ, I've had several friends pass drug tests, and they were the ones driving me and my friends around. They used to smoke, but hadn't in several months and we always hotboxed there cars. He never got high, although I think he was acting goofy just to fuck with us sometimes. One is a paramedic now, and the other works with handicapped folk. They both had piss tests, though.