Black coffee I've heard. I'm only going by hearsay. I've never had a hangover. Back when I used to party if I had too much to drink I'd puke it all out. I never retained enough alcohol in my system to have a hangover the next day.
Take a couple of Tylenol, eat a LIGHT breakfast, nothing greasy, and have either tomato/V-8 juice or orange juice, something with vitamin C, and push fluids--lots of water and/or juice, but stay away from carbonated drinks. Last, even though it's hard and a pain, get outside and walk or even run, if that's your thing. Drinking the fluid and then sweating will help to flush the toxins out. And the sooner you do that, the sooner you'll be on the mend.