McDonald’s lovers had their minds blown after seemingly learning the purpose behind the buttons on the top of drink lids. This week, a video posted on the popular Twitter account Today Years Old went viral after it showed the reason for those fun-to-pop buttons on every McDonald’s soda. The plastic buttons – sometimes labelled “Diet”, “Cola”, “Tea”, and “Other” – allow workers to indicate what the customer ordered so that they’re given the correct drink. For example, if someone ordered a Diet Coke at a McDonald’s drive-thru, they’d be handed a drink with the “Diet” button pushed down on the lid, while the other buttons remained unpopped. However, true fast food fans will also notice the rectangular buttons on the plastic lid. In the viral video, which has more than two million views, a person shocked McDonald’s fans when they pushed down on the wrong circular button and used the rectangular one to correct their mistake. “I was today years old when…” they captioned the clip, which showed that if the rectangular button was pressed, the circle next to it immediately popped up. In the comments, many users concluded that the plastic lid is used like a “reset” button – if an employee accidentally indicates the wrong drink preference, they can use the rectangular button to make sure the customer is given the right drink. “What kind of sorcery is this?” tweeted one mind-blown person after discovering the purpose behind the plastic button. “This is a lie! This can not be true!?!?! Can it???” another user jokingly asked. “At this point I don’t even think I’m breathing correctly,” said someone else. Others took the opportunity to seemingly confirm the purpose of the button, with one person writing: “The cap is to mark what the drink is (let’s say the diff between Diet Coke and Coke) this allows you to redo if you pressed the wrong one.” “There is an undo function,” one person replied, while another said: “Whaaatt? Those were reset buttons?” Most recently, fans of the American fast food chain expressed their disappointment after learning “why McDonald’s fries taste different than everybody else’s fries”. TikTok user Jordan, who goes by @jordan_the_stallion8 on the app, revealed that McDonald’s beloved fries are cooked with “natural beef flavour”, making them not suitable for vegans. “It’s because McDonald’s cooks [its] fries with beef flavouring mixed within their vegetable oil,” Jordan said. “So that’s why the fries taste so good, but also so different from everybody else’s.” @jordan_the_stallion8 #stitch with @youraveragetechbro #fypシ ♬ original sound - Jordan_The_Stallion8 The TikToker then noted that the revelation was probably “bad news for vegetarians”. The realisation upset many vegan and vegetarian customers, with one person commenting: “Wait.. whaaaat!? I’m vegan and all I can eat from McDonald’s are fries.” “WTF. Never again,” another said. Others revealed that it is a well-known fact that McDonald’s fries are not vegan in the US. “I thought everyone knew this,” said one person, while someone else wrote: “This has been known for at least a decade.” The Independent has contacted McDonald’s for comment. Read More McDonald's found liable for hot Chicken McNugget that fell from Happy Meal and burned girl Woman shares dismay over ‘mouse-sized’ panini she purchased for $8 on vacation in Italy McDonald’s fans upset after ‘expert’ claims he knows why fries taste different What is coronation chicken? The story of the royal recipe and how to make it Woman shares dismay over ‘mouse-sized’ panini she purchased for $8 on Italy vacation Gordon Ramsay puts his spin on a traditional Maori dessert