You’ve stopped into your favorite cafe, fast-food spot, or even your go-to gas station for a quick liquid treat. You order up your usual — a coffee, slushie, soda, whatever it may be — to go, and you’re on your way. But as you head out the door, you notice something on the top of your cup. A few little bubbles are imprinted on the top. Some were pushed in by your barista, while others were left alone. Why? And what exactly are these bubbles on your fountain cup or coffee cup lid? 

The first reason is a rather practical one: It helps the register attendant, barista, or waitstaff member keep track of which drink is which. Some lids, especially those found on plastic cups at fast food restaurants, are often used to distinguish diet from regular soda and are even sometimes labeled with “tea” or “other” to indicate which drink is inside, The Independent explained in a 2023 article. In coffee shops, these may more often be labeled with “decaf” and “regular” to keep track. 

However, the buttons can get even more specific, with some indicating customization to the drink — like “no ice,” “milk,” or “sugar.” This way, not only does the server know what drink they’re handing you, but you also know that they got your custom drink order right before you even take your first sip.

But, as a 2021 viral clip on TikTok revealed, sometimes, soda fountain lids contain one more secret: a reset button. 

“I was today years old when …” the clip begins. And you see someone simply pressing down every circular button on top of a soda lid. Then, like magic, you see the same person press on the raised rectangular buttons toward the outside of the lid, which raises the circular buttons back up again, resetting the entire lid. “All this time wasted not doing this on road trips to annoy my siblings,” the user added in the caption.

So there you have it, the easy answer to why your lids have all those fancy buttons. Now, all you need to do is gather your siblings and incessantly annoy them by pressing and resetting the button as fast as you can too.