Everyone needs to know that the supermarkets are only closed for one day. This does not mean that you are going to die if you don't to go shopping. We all know that over the days of Christmas you will not be eating all 10 loaves of bread or drinking the entire 15 litres of orange squash that you must so desperately buy before Christmas day.
Personally, I refuse to go to any supermarket if there is even a chance that it will be busy, just for the simply fact to avoid these types of people.