Check this out from Dvice.com

Shrinking Jug Keeps Milk Fresh For Another Week

That is so cool!  I want one.  All you do is pour your new gallon of milk into it and then close it.  When you want some milk you just push the button and the milk pours into your glass or cereal bowl and the container shrinks in the process.  Since we always buy 2 gallons of milk I think it would be appropriate to buy 2 of these.  Although if one of these containers cost $20 – $100 then perhaps 1 will do lol.

It works by keeping the air out so when you open the milk it starts going bad because the air does something to it… just read the article, it makes more sense when they say what it does.