The worst possible thing you can do when you’ve drunk too much is consume coffee. Caffeine is a diuretic, and what you need to get over a hangover is hydration. Dehydration is the main reason you feel like a heaping pile of festering crap after drinking too much. In the movies and on TV, a sober person always suggests that the drunk person should have some coffee. All this does is make a person drunk and hyper. Of course, the best thing to do is not to overdo it with alcohol at all.
Nah . . .
If you do go overboard with drinking, the best thing to do is just get back to eating normally and drinking lots of water. The important thing is to eat real food and stay hydrated. Cleanses might work for the short term, but they will ultimately harm your metabolism and don’t work in the long run. On the other hand, occasionally getting blotto will temporarily help you ignore the myriad ways you’re screwing up your life.