I assumed it was a joke. But Christmas time is not a good time to joke about drunks with me. In high school I woke on Christmas morning to hear that two of my best friends flipped a car while driving drunk, and one was killed.
There is no excuse for drunks that get behind the wheel. We are all in agreement on that.
Making drinking jokes or jokes/humor about drinking to the point of being drunk is fairly harmless.
Just as I need to recognize my own sensitivies to people making deaf or hard of hearing jokes/humor others have their sensitivities. Sometimes its best not to engage anyone but instead just walk away. Getting angry/frustrated/passionate over it and directing it towards the wrong people does not help.