When I drank, I found a 32oz cup of mountain dew and a snickers bar. Then sip water. Dehydration and a big swing in blood sugar levels cause hangovers. (Alcohol is very high in sugar regardless of type). So this gets some fluid in you and brings up your sugar level.
My grandad swore wake up hung over drink a coke and 3 beers. Well I found the mountain dew and Snickers to do the same thing.