Drinking milk from the fridge without first smelling to see if it's still good
Even worse on the morning after when you wake up still drunk, thirsty as hell and your mouth tastes like crap
Biting into the inside of your cheek when eating a sandwich.
I did it about an hour ago. #-o
Getting old
I did that with a bottle of extra strength grappa on holiday in Croatia this year. NastyOr worse, waking up the morning after drinking, reaching for a glass of water and finding out it is a vodka from the night before. One way trip to vomit town.