I had to take a mouth swap for a state job and no coffee does not work and I am a huge coffee drinker, see the thing is after 10mins. And sometimes not even that long the pores in your mouth cleanse themselves with your own saliva, this is not a myth either my sister works at Bristol, TN hospital and actually I had asked the same question but it wasn't coffee!!
From Deena...Drinking coffee does nothing. Don't be offended but I am assuming that you must be in your teens or early twenties. If you are concerned about passing the test you have two options... Number 1 do not do what ever you are taking.....number 2 put a little bit of bleach inside of your mouth without anyone seeing....number 3 pray to Jesus . Sincerely, Deena