Back before I discovered the best high calorie shake, I would put anything and everything in a shake. Mostly milk, ice cream, eggs, strawberries, chocolate syrup, protein powder, among other things.
Now, I take Muscle Juice which is as high calorie as it gets. Don't take it if you don't want a full day's worth of fat, minimum. It has 40 grams of fat, like 200 carbs and about 100 grams of protein. It's hard to finish the first 5 times.
Even with skim milk, a serving is 4 scoops, with 6 cups of skim and your looking at 1500 calories. I haven't bulked or taken a huge shake since last summer.
2000 would be bout 6 cups of milk, 2-3 cups of ice cream, syrup, a banana and an egg or 2, plus any kind o protein powder, I take myoplex and muscle milk as well. I could kill for a shake like that right now, but I'm too lazy.