I was flipping through some old photos of Iran the other day when I came across some photos of food, and it got me thinking about ordering in restaurants- specifically, ordering soft drinks.
In the U.S. (as in most places) you order a Coke, Diet Coke, Sprite, etc. In other words, you order them by name. In Iran, however, you order by color: سیاه siyah black, سفید sefid white, and زرد zard yellow. Black is Coke/Pepsi, white is Sprite/7-Up, and yellow is Fanta. Pretty logical.
I remember anytime we went to a restaurant, my uncle would take drink orders. We'd all order by color, and then he'd review, "So that was 4 black, 3 yellow, and 1 white drink?" Or else he would simply ask, "Chand ta siyah? Chand ta sefid? How many black? How many white?" And we'd answer.
I also saw a great example of this over the weekend when I watched the movie Pole Choobi, The Wooden Bridge. The friends are sitting down to eat, and as he's opening the bottles, Bahram Radan's character, Amir, asks, "Bacheha ki che rangi mikhoreh?, Guys, who's drinking what color?"
This is not to say that you can't order by name. Of course you can order a Coke, and many do. But
خواهی نشوی رسوا همرنگ جماعت شوkhaahi nashavi rosvaa, hamrange jama'at sho, if you don't want to be disgraced, do as others do (literally, become the same color as the crowd).
or, when in Rome (or Tehran), do as the Romans (or Tehranis.)