I don't know what it is, but I frickin love milk. It's one of my 4 main liquids (water, milk, coffee, beer) I put down a gallon about every 4 days. In college, I'd drink a half gallon a day. Usually when I eat anything that makes me thristy/is a little salty, like red meat, I"ll crush the milk too. Pasta? it's so carby, I've got to have milk to get some protein to level out the glucose release. Hungover? not only does milk rehydrate me, it gives me much needed calories/energy. Why I'm so dependent, I have no idea. Friends and family know to stock up on extra milk when I visit. It's like water to me. I can't explain why, or how I got to this point.
edit: Growing up, we always had 2% in the house. From college on I drink skim, occasionally (once every few months) I get 1 or 2%, just to up the fat content (I'm a runner, not terribly concerned with weight gain, more or less trying to maintain body mass...)