Milk is a resource in Cookie clicker. You can obtain more milk by unlocking achievements. To choose a flavor, you need to click Legacy and press yes. The persentage of your milk can go higher than 100%.
Some regular flavors of milk are Plain milk, Chocolate milk, Raspberry milk, Orange milk, Caramel milk, Banana milk, Lime milk, Blueberry milk, Strawberry milk, and Vanilla milk. Some special examples of milk are Zebra Milk, Cosmic milk, Flaming milk, Sanguine milk, Midas milk, Midnight milk, Green Inferno milk, and Frostfire milk.