Fans of fast-food giant McDonald’s are suddenly looking at their drink lids a little closer after it was revealed exactly what the ridges and buttons on top of them do. Each circular button is labeled with a different drink, including “diet,” “cola,” “RB” (root beer), or “Other.” Next to each round button is a smaller, rectangular button, which serves its own, lesser-known purpose. If a server has clicked down the wrong circular button — say a cola instead of a diet cola — they can reset the lid by clicking on the ridge next to the button they’ve pressed and start all over again. The lids differ from country to country. While root beer is popular in the U.S., it’s not served in many other countries. In some countries, a numbered code is found on the lids — (1) represents no caffeine and (2) represents diet drinks.
