Carbonated Milk?

I had a milk man that came around the block, dropping off milk every couple days. One day I am playing outside and this guy walks by and says "Howdy partner, just here with your daily dose of milk." When I saw him drive away, I looked through the back of the van and saw some off colored milk. I asked him the next day what it was and he explained it to me that it was an odd request for a neighbor down the street. Now I have never seen this neighbor but he lived in a large house. The lights were always off and the windows were always closed. It seemed vacant. Too this day I do not know why this bothered me so much, Just a guy ordering strange milk, whats wrong with that. But curiosity got the best of me and I rang his doorbell the next day. The door creaked open but no-one was insight. I make my way to the kitchen and open the fridge. Bottles and bottles of milk. I opened one up and took a drink, this wasn't regular milk. It was cold, but fizzy, almost....carbonated. Before I had time to collect my thoughts i heard the door slam behind me. I dropped the empty bottle and ran outta there as fast as I could. I returned back to my house and waited. I asked some neighbors if they new about the guy the next day, however no one knew what I was talking about. I hopped on my bike and rode back to the guy's house but all I saw was an open field. It started to rain at this point but I pushed on to find something. It started raining hard and in the middle of the field I found an empty bottle. I tried finding the milk deliverer but the company did not seem to exist. Its been years, decades maybe, since the incident but I have always been fascinated by the carbonated milk. I've been living wealthy and have a large house, built on the empty property to learn more about the mystery, but have spent many days alone with only the company of the neighborhood milkman to bring me my special order of Carbonated milk.