Aut cum scuto aut in scuto
Must be water. It's a pretty neat trick when the temp gets down about -40 or lower. We got yelled at once when I worked in Fairbanks, AK for using coffee to do this. It never occurred to us that hot water works just as well - and costs LOTS less.
Does not have to be that cold...about 0 will do it.
hot shower on a cold day. boiling hot water works best-unlike election laws, the laws of thermodynamics cannot be disobeyed.