For what it’s worth, they didn’t come up with any of these terms. Americanos have been around since WW2 or so; Flat Whites are a popular Australian/NZ drink they brought over. And “skinny” and “dry” are in widespread use well outside of coffeehouses.
Fun fact: the reason “tall” means “small” is that when they opened, the two size choices were “short” (small) and “tall” (large). But ‘short’ wasn’t popular, so it got dropped from the menu, and they added “grande” and “trenta” as people demanded bigger coffee sizes.
