There is a myth that if you drink coffee after drinking too much alcohol, it will help you get sober. Unfortunately, this is a lie that can get you killed. Drinking coffee does nothing to help fight off drunkenness. The only thing that will help you get sober after you drink too much alcohol is to wait it out. That could take a few hours or it could take all night. Coffee won't make a bit of difference to whether you get sober before you get in your car to drive.
The main reason that you should not rely on coffee to help you sober up is because coffee is what many people drink to stay awake. Caffeine in coffee will wake you up a little bit and that could be dangerous for a person who thinks that it is making them sober when it is doing nothing to help that cause. Being more awake is quite different than being more sober. The two have nothing in common, but when you are under the influence of alcohol, you may not realize the difference. Thinking that you are more sober than you actually are and getting in the car to drive is about as dangerous as it can get.
According to studies, the idea that coffee reverses the affects of alcohol is more than likely incorrect and dangerous to drinker's who believe the myth that they can somehow continue to drink alcohol as long as they drink coffee afterwards. It is dangerous in more ways than just driving though. It could convince the drinker that he/she can continue drinking alcohol to the point of alcohol poisoning. This could, in fact, lead to death. Drinking coffee in order to sober up is a bad idea for many reasons. You have to be careful about the combinations of drinks that you put together. The caffeine in the coffee can actually block important natural anxious feelings about whether you should continue to drink, whether you should drive and can keep you awake much longer than you need to stay awake when you are drunk.
Always remember that if you are going out to drink alcohol, you should always have a designated driver with you. Though you may get away with drinking and driving once or even twice, but eventually you will get caught which comes with a high price in insurance and court costs including a possible jail sentence. You could also cause an accident that kills or maims someone else or yourself. That is definitely not worth testing the coffee drinking with alcohol to reverse the alcoholic effect. Act responsibly when you are drinking and everyone will stay safe barring any hangovers you may have the next day.