I currently work for these guys:
http://www.detoxforless.com, which is a reseller for Spectrum Labs, the worlds #1 detox retailer.
Without sounding too cocky, I prolly know the most of anybody on these forums short of anybody who actually works in a testing lab.
First off, don't follow any of these stupid DIY suggestions. At worst they will get you sick, and at best they will non give clear results on the test resulting them either making you take the test again, or getting a positive result (which is bad) for a masking agent.
If you had more than 5 days to prepare, you could get it out of your system naturally...This shit depends on all kinds of variables (how often you smoke, your metabolism, what kind of test you're taking, etc..)
Anyways, we have a whole line of products, all of which work if you use them right. The drinks work if you're not a super heavy smoker and have at least 1 hour 1 prepare. But if you don't follow the instructions on the back, then you will prolly fail.
Anyway, go to that website, call the #800 number and the girl on the phone will tell you excatly what you need for your situation. And they offer overnight shipping.
I'm not trying to push their products or anything, I don't make any more or less dough if you buy, but I DO know that shit works and they've been in business for a long time.