Also, if you don't like the clumps... don't shake. Stick a tiny spoon in there when you first open the carton, and get the clump, and drop it in your coffee the old fashioned way.
Voila, fewer clumps in the rest of the milk.
My dad grew up on a farm, and they got their milk straight from the source. One time when we were having coffee together I said that must have been wonderful having fresh cream like that. His response was, are you crazy? We couldn't afford to keep that. The price for cream was so good we had to skim it and sell it. We drank what remained. (i.e. fresh skim milk).