Won't help his handover as such.. - But i seem to remember the colour of the drink is a rule of thumb to how bad the next day will be. - (something scientific i seem to remember about brewing and chemicals).
So if you stick to the light coloured drinks - vodka etc - your hangover is better than the darker drinks - That and drink a good amount of water before you go to bed - as it stops dyhydration which causes the pounding headache.
Seemed to work when i was a student a few (ahem) years ago - Although the worse hangover ever envolved very cheap white wine. So perhaps it's all just all load of tosh!