Champagne (preferably cheap), that has sat out all night at a party so it ages a bit more and tastes more like beer. Should be consumed at room temperature as you wake up, hung over, at 1 p.m.
Note: When orange juice is added, the mixture is known as champeerosa.
Sally: Ooo my head hurts....I really need some hair of the dog. Did we drink everything?
Jill: Nah, we got some champeer. Down it.