When it's last call...
Skip the brandy, whiskey, red wine—all of which have a higher concentration of congeners, chemicals believed to worsen alcohol's effects. Instead, stick with a nightcap with a lower concentration, such as a lager, gin or vodka. The best choice? A lemon-lime soda. A recent study from China showed that a carbonated, sugary, lemon-lime beverage (similar to Sprite or 7Up) helped liver enzymes metabolize alcohol faster, reducing the production of acetaldehyde, the toxic byproduct of alcohol and a suspected cause of hangovers. Keep in mind that this study was done in dishes and test tubes in the lab and not on real, live, intoxicated people, so experts are still hesitant to call lemon-lime soda (or anything, really) a proven "cure" for hangovers. Nevertheless, the liquid in the soda is rehydrating, and the sugar can give you some energy for the trip home.
When your friend offers you a cigarette (because she knows you only smoke when you drink)...
Tell her about this Brown University study that found that university students who smoked while drinking were more likely to wake up with severe hangovers than students who drank the same amount but didn't smoke.
When you arrive home and get the munchies...
Root through your kitchen cupboard for a can of chicken soup. The broth will help you replace lost fluids—not to mention the potassium and salt you've lost while repeatedly ducking into the ladies room—and the noodles are easy to digest.
Next: The benefits of going straight to bed