If you've had too much to drink, no amount of coffee, soda, water or anything else is going to sober you up. The only thing that will do the trick is time. The liver can metabolize only about one standard drink (12 ounces of beer, 6 ounces of wine, or 1.5 ounces of hard liquor) per hour, so if you're drinking more than that every 60 minutes, you'll have alcohol in your system for some time. The idea of coffee's sobering effect may have started because caffeine acts as a stimulant, counteracting the sedative effect of alcohol to a small degree. However, it has no effect on the amount of alcohol in the blood. So if you've been drinking, spend your money on a cab rather than a cappuccino.