What Does Water Have to Do With It

Here's a good one from the website (The Customer is) Not Always Right:

(I’m visiting a friend of mine at work when this exchange occurs.)

Customer:*notes my friend’s nametag* “Matt-ie-oh… what a neat name, where’s it from?”

Friend: “It’s pronounced mah-tay-oh, actually. It’s Spanish.”

Customer: “Oh, really? You don’t look Mexican.”

Friend: “I’m not, I’m Spanish.”

Customer: “Well, what’s the difference?”

Friend: “The Atlantic Ocean?”