a hair of the dog
the hair of the dog (that bit you)
An alcoholic drink consumed to remedy a hangover. The phrase comes from the notion that literally rubbing the hair of the dog that bit you on the wound would help it to heal. Wow, all that beer has left me feeling terrible this morning. The only cure is the hair of the dog, I guess!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a hair of the dogSPOKEN
A hair of the dog is an alcoholic drink that someone has to try to make them feel better after drinking too much alcohol the day before. I need a drink, chum. A large hair of the dog. Note: You can also talk about a hair of the dog that bit you. Now he was feeling worse and wondering if a hair of the dog that bit him might not set him up for the day. Note: There was an old belief that if a person was bitten by a mad dog, they could be cured by putting some hairs from the dog's tail on the wound.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012