I think you're talking about Goldenseal, an herbal derivative known for it's cleansing properties.. Here's a pretty good explanation:

Does Goldenseal work?

Goldenseal does nothing to remove marijuana from the body. People that used Goldenseal and passed the drug test passed because of the extraordinary amount of water that is consumed with Goldenseal. Excessive fluid intake can result in the reduction of creatinine levels in the urine and result in the sample being considered too dilute.

http://www.bdtzone.com/false_positives.asp
Mello.as.Hello Reviewed by Mello.as.Hello on . DRUG TEST HELP Okay today i had an interview for a job and i didnt know they did i drug test so i didnt prep. First off i had the oral test that you stick in your mouth, so i heard from a friend if you stick it under your tongue instead of between your gums and cheeck it will work. And i think it might be true because i stuck it under my tongue and the lady said that it was veryy important i stuck it in my cheeck and i secretly put it back under my tongue. Last time i smoked was Friday. Okay so my first Rating: 5