Hundreds of concertgoers flooded social media with videos and photos from the opening night of Charli XCX and Troye Sivan’s highly anticipated “Sweat Tour” on Saturday. Posts captured Charli XCX’s dramatic entrance from behind a lime green “Brat” curtain to her performances of songs such as “360” and “Apple” that served as the soundtrack of the “Brat Summer” phenomenon. 

But one of the most viral videos from that night doesn’t feature Charli XCX or Sivan. Instead, it focuses on a small group of people donning masks of the Duolingo mascot, Duo, with the video’s creator asking viewers via on-screen text, “Does anyone know why a group of duolingos attended the sweat tour?"

The question posed in that video, which has racked up more than 2.1 million views and nearly 470,000 likes on TikTok as of this writing, has a simple answer: It’s the latest instance of Duolingo pulling off a marketing stunt during a buzzy pop culture moment, sparking an utpouring of user-generated content documenting its mascot’s shenanigans. 

“We’ve previously just seen a ton of success activating at major music events,” Duolingo’s Global Marketing Campaign Director Michaela Kron told Ad Age, pointing to Duo’s appearances at Taylor Swift’s “Eras Tour” concert in Pittsburgh last June and K-pop boy band Enhypen’s show in New Jersey in October. “We know that there’s something there when we tap into these specific fandoms and around these highly anticipated events in culture. So, when we heard about the ‘Sweat Tour,’ especially on the heels of ‘Brat Summer’—obviously, you couldn’t go anywhere without hearing about it—it really felt like such a natural opportunity for us to plug in.” 

It didn’t hurt that Duo is the same shade of “Brat green” as Charli XCX’s album cover, Kron said. And one song on the album, “Talk Talk,” references the idea of speaking multiple languages with the lyrics, “Talk to me in French / Talk to me in Spanish / Talk to me in your own made-up language / Doesn't matter if I understand it.”

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Kron, along with Duolingo Social Media Content Creator Kelsey Dempsey and a handful of others on the brand’s marketing team, pulled the stunt together in just over a month. The team scrambled to secure “as many floor tickets as possible” to the show in early August, Kron said, roughly four months after tickets to the tour first went on sale. They then recruited more than 20 employee volunteers, including from its engineering and product management teams, to attend the first night of the “Sweat Tour” at Little Caesars Arena in Detroit on Sept. 14. 

“We wanted to take advantage of the very first show of the tour because we knew that there would be a lot of attention and a lot of hype around that,” Kron said. It would also give the flock of Duos more opportunities to appear in social content as concertgoers painstakingly recorded every moment of the first stop on the tour. 

Dempsey orchestrated the majority of the stunt, standing at the front of the volunteers and directing them when to put on and take off their Duo masks, she said. She and the team landed on the songs “Apple” and “Talk Talk” as the opportune moments for the group to don the masks—“Apple” because of its TikTok virality—more concertgoers would have their cameras out—and “Talk Talk” because of its language-related lyrics, she said. 

Initially, Dempsey was uncertain whether the stunt would be caught on camera. “When we were in the pit, no one was really filming us, so we couldn't tell if people were actually paying attention,” she said. 

While she couldn’t see it at the time, dozens of attendees who weren’t on the floor were filming the Duos from higher vantage points. At the very end of the concert, Charli XCX herself not only noticed the flock of green owls but shouted them out, saying, “Duolingo right there, baby.”

While Dempsey herself didn’t capture clear footage of the artist acknowledging Duolingo’s stunt, another audience member did, so she asked for permission to use the footage, she said. She then edited that clip together with a video she filmed where the camera swivels to face the group of Duos dancing in the crowd. The resulting video, which also includes on-screen text reading, “even charli xcx [is] giving duolingo reminders 💀 [skull emoji],” has since garnered nearly 5 million views across TikTok and Instagram. Charli XCX even reposted the video to her TikTok account, Dempsey said.

Duolingo’s “Sweat Tour” stunt ultimately generated more than 20 million impressions, 13 million of which resulted from the content shared by other concertgoers rather than the Duolingo social channels, Dempsey said. The brand has seen more than 2,200 mentions of “Duolingo” and “Charli XCX” over the past several days, she said. 

Some of those impressions stemmed from two videos Dempsey posted on her TikTok. One of them, where she simply filmed herself standing in front of the flock of Duos and added text reading, “when your job is to bring duolingos into sweat tour opening night 😭😭 [two crying laughing emojis],” has amassed 1.4 million views.

Social content surrounding a marketing stunt such as Duolingo’s “feels more authentic coming from the people who are on the ground rather than Duolingo posting about it,” Dempsey said. “It’s kind of a new evolution of guerrilla marketing” for the TikTok era, she added, where “you do as much as you can to create that experience that is [also] the content.”

Outside the show 

Duolingo’s “Sweat Tour” marketing also extended beyond its mid-show stunt. Duo himself appeared outside the concert venue in a “Brat” T-shirt about two hours ahead of the show, joining Kron and team members to hand out shirts, signs and other merch featuring a “brat-ified” version of Duo, Kron said. After about 30 minutes, security told them Duo couldn’t be on the property and moved them across the street from the stadium, she said. 

“But what was so interesting was that people got out of line and came to us,” Kron said. “People were willing to step out of line and get their photo with Duo.”

Dempsey also leveraged the comedy of Duo being kicked off stadium property for a post on X. In response to a post from a Charli XCX fan announcing Duo had been ejected, she wrote, “they kicked me out so i multiplied.”

Following the stunt, several people sent DMs to Duolingo, asking if the mascot or his owls will appear at other stops on the tour. They were sent a PDF file with the design of the Duo sign, Kron said, in case they want to bring them to shows they are attending. Duolingo has no immediate plans to repeat the stunt at other shows

“That’s the bigger point here—we always want to show up as true fans, not as a brand in a way that feels forced or cringe,” Kron said. “That’s why we really take great care to ensure that whatever we're doing really fits and makes sense [for Duolingo], not just this random brand showing up opportunistically."