Most people probably know what the little round buttons on the top of fast food soda lids are for, since they are generally labeled things like "cola," "diet" and "RB."
But it turns out the little rectangular doodads near them on some lids also have a function.
Some may have assumed that those little rectangles were just to maintain structural integrity in the lid, or something leftover from the process used to make the lids, but they actually have their own use. Those little rectangles let you reset the dots if you make a mistake and push the wrong one in.
For instance, if you pushed the round "diet" button but the cup is actually full of regular cola, pushing on the little rectangle next to the "diet" dot will pop the plastic back up and let you depress the "cola" button instead.
This revelation was evidently mind-blowing for a whole lot of people.
Some were excited by the news, while others were just flabbergasted.
A few people in the comments said the fact that pressing on that bit of the lid would reset the button indicating the drink's flavor was completely coincidental.
They claimed the small rectangular bits are actually there for another purpose like making sure the lids don't get crushed when they are stacked or making the liquid inside slosh around less.
Not all fast food chains use the same lids, so your mileage may vary.
Whether the lids were intentionally designed to have an undo feature or it's just a happy accident, it works so we'll take the W.
The more you know...