It should be the one nostalgic experience. “Everyone remembers their first Happy Meal as a child,” said the fast-food chain McDonald’s, explaining the decision to now also offer the Happy Meal, which is popular with children, in a version for adults. But apparently the run on the shops had simply been underestimated.

McDonald’s employees report this on a wide variety of social media. “The new Happy Meal for adults is killing me,” complains a Reddit employee. The rush is so gigantic that menus have to be prepared for Halde before the opening. “I hate it,” complains the affected person.

That seems to be the prevailing opinion among employees. According to an employee, the demand is so great that the shops simply cannot keep up with serving, an employee told “Kotaku”. “The biggest difficulty is the sheer volume of menus we sell. Most stores either sell out the boxes, Big Mac buns, or the toys. Many stores sell out more than one.” Another employee confirms this. “We had a line around the block on the first day,” he tells “Insider”. “By 6 p.m. the boxes were sold out.”

In its combination, the adult Happy Meal brings with it several possible bottlenecks. The collaboration with trending clothing brand Cactus Plant Flea Market consists of a special box, an included collectible toy and a menu consisting of a Big Mäc or a ten-pack of chicken nuggets as well as a portion of fries and a drink.

Every single element can create bottlenecks, employees say. Running out of toys is just the most obvious. The boxes are difficult to stack, so you can only prepare them insufficiently for the onslaught. But the food also proved to be a surprising hurdle. “We’re basically waiting for nuggets all the time,” complains an employee at Reddit. While the children’s menus with a hamburger and a four-pack of nuggets would require little effort, the Big Mäc and the ten-pack of nuggets are more complex to prepare and require more ingredients. And thus led to kitchen traffic jams. “My manager ordered 43 medium portions of fries earlier. I was speechless.” At Tiktok, an employee shows the extent of the chaos this has caused.

The fact that McDonald’s worked together with a trendy company and thus brought out a quasi-guaranteed collector’s item is probably only part of the phenomenon. While children can only occasionally beg for a children’s menu, adults need only make their own decision to purchase – and march to the nearest store. The company does not seem to have expected the corresponding rush and its consequences for normal business. “We’re selling at least two to three times as many Big Macs as usual,” complained an employee at Kotaku.

However, there is no quick end in sight. Although the ingredients of the menu are often sold out, the company has still not called off the campaign itself: it will run until the end of the month. And will then be seamlessly replaced by the Halloween campaign.

Sources: Insider, Fortune, Kotaku, Reddit, McDonald’s