That doesn't sound very smart. red bull is full of niacin. A lot of people commonly believe niacin can "flush" drugs out of your body. Niacin is an OTC medication that people with high cholesterol use. It's very effective for cholesterol management but has never been proven effective to flush out drugs. It can be dangerous too. It can cause flushing, high heart rate, etc and combined with the amount of sugar and caffeine in red bull, do NOT start chugging red bulls. If you're still determined to try the niacin theory, go buy some niacin (vitamin B3) at a drug store in lieu of the red bull and take the recommended dose. Take it with a little snack before bed. Don't start popping a bunch of them thinking that will make the process faster because that could land you a trip in the hospital. XR niacin causes the flushing which can be uncomfortable. My advice: stop smoking now and be responsible. Drink lots of water, exercise, and buy a home screening test for marijuana (~$15 for a pack of 2) from a local drug store. Time is the only proven effective method of passing a drug test.