Mixed Drinks

What causes a child to decide that he wants a mixed drink? When we buy a fountain drink at the convenience store, my oldest always wants "orange" but my youngest changes it up a bit:

One day it might be Sprite.

The next - a little bit of Sprite and the same amount of Pepsi.

The next - a little bit of Fruit Punch and the same amount of Coke.

And my favorite - a little bit of Sprite, a little bit of Fruit Punch, a little bit of Pepsi and a little bit of Coke!