What is the most effective way to sober up after drinking?

The most effective way to sober up after drinking is indeed time. When alcohol is consumed, the body metabolizes it at a relatively fixed rate, generally about one standard drink per hour. This means that regardless of any other actions taken—whether it be drinking coffee, taking a cold shower, or eating a meal—time remains the only factor that effectively reduces blood alcohol concentration (BAC) levels.

Drinking coffee might make someone feel more alert, but it does not actually speed up the elimination of alcohol from the bloodstream. Similarly, taking a cold shower might provide a refreshing sensation but has no impact on the body's rate of alcohol metabolism. Eating a large meal could slow down the absorption of alcohol if consumed before drinking, but it does not help in removing alcohol that is already in the system. Hence, allowing adequate time for the body to process the alcohol is the only true method to achieve sobriety.