I had this thing I got off my mum. As a single mum she would buy the largest cartons of milk we have in english stores (about 6 pints) because they were cheaper per pint. However, there were only 3 of us in the house, so she would look for what she called "a good date" so that we would have as many days as posible to drink it in before it went funny. No good having 6 pints of milk go off before we can drink it, would be wasting precious money. As we reached our teens, she would send us to the local convenience store for a bottle of milk and we would be told to check it had "a good date on it". The funny bit is when I grew up and left home. I am the only person in our house that drinks semi-skimmed milk so it is even more important to get a good date on the milk, but my darling didn't know what I meant by this. So after about a year, one day in the dairy ailse, he asks me what I mean and I explained it. He wondered if it was like a wine vintage being a good year, wether milk from a wednesday is better than a saturday or something, but once he knew he understood.