Having just attended my office party last night, here are my tried and true:
1. Two large glasses of water before bed.
2. DO NOT stay in bed all day.
3. One large glass of orange juice in the morning, with two Advils.
4. Go for a walk to your nearest greasy restaurant for breakfast, preferably Kentucky Fried Chicken (IMPORTANT: Remember to bring your sunglasses).
5. Phone everybody who you may have had contact with last night and apologize. You probably said or did something horribly wrong or perverse.
Hair of the dog? I think I'd almost rather take that literally than the way in which it was meant.