Green Milk is is OK if you like citrus. I prefer the Blue Milk.
But I heard there was a scene cut from The Last Jedi where he explains the blue milk and green milk origins to Rey.
Rey: "I saw you milk that sea cow thing for the green milk. Where does this blue milk I'm drinking come from?"
Luke: "Same creature, they are hermaphroditic."
Rey: "But the green milk came from the udders, I saw it."
Luke: "Yup"
Rey: "Then the blue milk is from the....oh God, [gagging sound]."
Luke: "Let me tell you about the birds and the bees and where babies come from...."