It was so common in the movies of the 40s and 50s for someone to be served coffee to sober them up fast that we all as a society believed it to be true. Get drunk. Drink Coffee. Drive home. Not cool. The only thing that sobers you up is time. Time for your liver to process the alcohol in your blood, to degrade it and remove if from your circulation so that you can think clearly and react quickly once again. Coffee, on the other hand, is full of caffeine which is a stimulant. IT makes you feel more alert, but in fact you're still drink with all that comes along with that; bad decision making, slow response time, and perhaps dancing around wth a lamp shade on your head. The trouble is you're more alert so you think you can do anything, like drive home. So actually, coffee and drinking is a bad combination. If someone you know is drunk and wants to drive, stop them. Don't give them coffee. Give them a large glass of water, to help with alcohol's dehydrating nature, a couple of aspirin and let them sleep it off on your couch.