Sobering up a drunk starts before any drinking takes place, long before the headaches and vomiting. It takes approximately one hour for an ounce of alcohol to pass through your body, and shortcuts around that process are few and far between. Planning ways to sober up a drunk before, during and after the drinking can help expedite the process and ensure that your party-hardy buddy is able to function as quickly as possible.
Make sure your friend eats while he drinks. Food helps absorb the alcohol, which facilitates a faster recovery. Some studies suggest that foods high in fructose, such as honey, Coca-Cola and fruit products like Fig Newtons, are especially good at countering the effects of alcohol.
Cut your friend off. It seems obvious, but every swallow of alcohol is a swallow your friend's body needs to process and oxidize before he can sober up. Once you recognize the need to clear out the booze in his system, tell him to stop drinking.
Give your friend lots of water to drink. Alcohol dehydrates the body, which is part of what makes a hangover so painful. Drinking a lot of water--even alternating glasses of water with alcoholic drinks--keeps the body hydrated and cuts the effects of drunkenness.
Get your friend to drink lots of coffee or energy drinks. Caffeine and stimulants don't actually prevent inebriation. In fact, they often make things worse, since caffeine is a diaretic that further dehydrates the body. However, they do help the mind concentrate. As a short-term stop-gap, caffeine can keep the edge off of drunkenness until other steps have a chance to do their job.
Induce vomiting. It sounds gross, but there's no better way to get alcohol out of his system quickly. Stick your finger down his throat, or describe the contents of the nearest trashcan (preferably if it contains discarded food scraps). Make sure there's a sink, toilet or bucket nearby for him when you do. On a more serious note, make sure his throat and air passages are clear after he vomits, so that he can breathe safely.
Give your friend a hangover pill. "Sober up" tablets sold at most pharmacies help the body process alcohol more quickly. If you don't have access to a formal hangover pill, provide him with a good multivitamin…especially one with plenty of vitamin B.
Let him to sleep it off. Even napping for a couple of hours can do wonders for eliminating drunkenness, and can get your friend back on his feet more quickly.