When McDonald’s recently rolled out its Grimace Birthday meal, it probably didn’t expect it would spark a trend of Gen Zers pretending to pass out or be attacked by the purple blob. But that is what is happening on TikTok, where the “Grimace Shake trend” is the latest brand-inspired social media trend to take hold.

Also read: 5 new TikTok trends that brands can follow

The TikToks start with someone (often a teenager) wishing Grimace a happy birthday and taking a sip of the shake. The video quickly cuts to the person passed out on the ground or against the wall with their face and chest covered in the milkshake. Some cough and sputter up the drink. Many of the videos are like mini horror films, shot in the dark on playgrounds or parking lots, or in cars. On TikTok the hashtag #grimaceshake has 370 million views at the time of writing.

McDonald's debuted the berry-flavored purple milkshake earlier this month along with a campaign featuring Grimace.

The TikTok trend seems to have taken a few variations. One seems to imply that the Grimace Shake has the same effects as lean or “purple drank,” a recreational drug drink made by mixing cough or cold syrup containing codeine and promethazine with a soft drink, that causes the drinker to become high, and slouch or lean. Another trend is more horror-focused, implying that Grimace attacks those who drink the purple milkshake.

McDonald’s has not responded to a request for comment, but has acknowledged the trend on Twitter with a photo of Grimace captioned, “meee pretending i don't see the grimace shake trendd.”

The reply came as a surprise to at least one marketing expert who presumed the Golden Arches would let the trend run its course without engaging. Before Grimace's response, Lia Haberman, who teaches social media and influencer marketing at UCLA, tweeted, “Sympathy for the McDonalds social team who can’t endorse or amplify this but have to be rolling on the floor.” McDonald’s U.S. head of social media Guillaume Huin replied to the tweet with “thank you for your sympathy” and a saluting emoji.

The willingness of McDonald’s to engage, however subtly, fits the social media approach it has used in recent years under creative agency of record Wieden+Kennedy to be less corporate, and a bit more freewheeling, as the brand seeks to cement its place in pop culture.

Also read: McDonald's and Burger King put up dueling outdoor ads written by ChatGPT

“This is what makes TikTok such a great platform for brands and marketers,” said Eden Lipke, director, strategy at creative agency Movers+Shakers, which does not work with the food chain. “McDonald’s goal was about reinventing Grimace, and making the beloved character more culturally relevant with a birthday limited-time offer. The brand’s community took it one step further ... likely driving a huge spike in sales and forever cementing this limited-time offer in the internet’s history.”

The trend also shows that no brand or product is safe from the absurd humor of the internet. The Grimace trend, while making an apparent drug reference, seems more harmless than other brand-related memes on social media. Consider the Tide Pods challenge, which saw teenagers dare each other to bite into a Tide Pod, a colorful yet highly toxic laundry detergent packet. The trend even caused Procter & Gamble to communicate that the pods only be used for laundry.

In May 2022, a Sprite challenge circulated on TikTok where people filmed themselves attempting to drink a whole bottle of Sprite without burping. Other internet-fueled trends have been more frivolous, such as the Wes Anderson film-inspired TikToks in which people shot their everyday errands in the style of the filmmaker.

The Grimace trend shows that brands have to stay on their toes, even days after a campaign launches, and have internal plans around positive or negative reactions.

“This is a good opportunity to have a conversation internally, from the top level, to the person running the day-to-day social channels, about what the brand is comfortable with and the level of risk tolerance,” said Haberman, the marketing expert who didn't expect McDonald's to respond to the trend. “Even the most junior employee should know that not all engagement is the best thing.”

While the Grimace trend has picked up speed in the last few days, it seems to have started with a TikTok by Austin Frazier, who posted a Grimace-inspired video on June 13, the day after the shake came out. Frazier’s TikTok bio says he is “The first victim of Grimace.” In the video, he excitedly wishes Grimace a happy birthday, and then the next shot is him sprawled on his kitchen floor with the drink next to him.

He later explained why he made the original video in a follow-up. He said the purple Grimace Shake reminded him of the “Spider-Verse” Whopper from Burger King that came out earlier this year and had a red bun with black sesame seeds. 

“I’m curious to hear how this plays out internally [at McDonald’s],” said Haberman. “I hope we get an oral history of this moment someday.”