Weed
This plant can last in a regular users pee for up to 12 weeks.
don't worry, all those one-time users, it only lasts 48 or less hours.
If all else fails, try saying you just used these:
Ibuprofen; (Advil, Nuprin, Motrin, Excedrin IB etc)
Naproxen (Aleve)
Ketoprofen (Orudis KT)
Promethazine (Phenergan, Promethegan)
Riboflavin (B2, Hempseed Oil)
Kidney infection (Kidney disease, diabetes) Liver Disease
Dronabinol (Marinol)
"drug tests have little to do with drug abuse,
and a lot to do with controlling workers
and weeding out undesirables." Abbie
Hoffman