There are a lot of factors...
How much you weigh. How fast your metabolism is. How often you smoke. How much fluid you take in.
Ideally, the person that would be able to get it out of their system the fastest is someone who: Is skinny, has a fast metabolism, doesn't smoke often, and stays well hydrated.
My buddy who was a heavy smoker found out 8 days before he was to be drug tested. He is in pretty good shape. He worked out every day - ran a couple of miles/swam laps on top of working out. He would also sit in the sauna for a little while each day. He passed the test.