Macca's cup baffles customers. Photo / TikTok
McDonald's is giving away a free glass that won't spill your drink – but some are "annoyed" by the cup's curious design.
It's a freebie designed to mark McDonald's Australia's 50th anniversary, but not everyone is a fan of the fast food giant's new souvenir glasses.
Last week Macca's unveiled six differently designed commemorative cups, available for free when you purchase a medium or large Mac Family Meal, or to be purchased for $4 a pop.
McDonald's told news.com.au that they have had an "overwhelmingly positive" response to the cups – but they haven't gone down well with every customer because of their design.
The glasses have a curved section on the bottom, meaning they wobble or tilt to an angle rather than sit flat.
"So has anyone got the new Macca's cup yet? That doesn't sit," TikTok user @nunya343 said in a video that has been viewed 469,000 times.
"I don't get it. I'm a bit pissed off as I wanted to use it as a plant holder."
But in a later video @nunya343 filled the cup up with water and spun it, attempting to get it to spill – but with no luck.
"All right, I'm impressed," she admitted.
Others had similar complaints, claiming it freaked them out or they simply didn't understand the design.
"As a person who spills things quite often, I appreciate this no-spill glass McDonald's," @thehappinesstrail wrote.
"But on day-to-day use do you know how annoying it is that they aren't flat on the bottom."
"Um … Thanks McDonald's! Not sure why I would want a glass that wobbled." @lisaandandy18 wrote.
"I actually like to call it the anxiety cup as it makes you feel like you're going to spill your drink the whole entire time," @alsfatfishing joked in his video.
"Look at it, it's ridiculous. Scariest thing I've ever had in my life."
But not everyone agreed with the complaints, with several people pointing out it was described as a "wobbling glass" on the packaging.
"It's called a wobble cup," one person commented.
"They're made like that; it's 'unspillable'," another wrote.
"It's supposed to be a no-spill, that's why," one person commented.
While they might be a little worry-inducing thanks to their spin action, @cleanwithnessa showed there was little chance of them actually spilling.
In a TikTok video she spun the cup – full of Coke – and a Coke can at the same time to see which one would fall down, with the can the only casualty.
"I bought a Big Mac just so I could get this free glass," she said in the caption.
A McDonald's Australia spokeswoman told news.com.au: "The new 50th anniversary collectable glasses are designed to wobble and swirl your drink without spilling.
"Free with any medium or large Big Mac, Grand Big Mac or Mac Jr meal, the glasses are fun, fearless and not afraid to be a little different.
"We are pleased to see an overwhelming positive response to the glasses, with customers appreciating their quality and novelty shape."
Why do Macca's cups wobble?
It's all in the design, with the curved bottom "designed to swirl your drink, but won't spill", McDonald's said in a statement announcing the cups last week.
The swirling glass design isn't new either and is used by whiskey drinkers to see the drink's composition and catch a good whiff of its scent.
McDonald's swirling glasses come in six designs: Big Mac, Cheese Melt, loose fries, packet fries, sesame seeds and a Macca's cup.
"Due to their popularity, stock is expected to run out with limited items available across the country," the McDonald's spokeswoman said.