Whole (homogenized) milk. I love the taste of whole milk, so rich and creamy, but I have to avoid it because I break out with terrible acne cysts when I drink it. In addition, I am lactose intolerant, so drinking it does a number on my stomach. :(
Oddly enough, I used to drink whole milk by the glasses when I was a kid, and it never really bothered me, but as I grew into an adult, I became less tolerant. I now drink a brand of milk for lactose intolerant individuals, and it’s skim milk too, so the fat content doesn’t cause me to break out or raise my cholesterol level.