As the weeks before my trip dissolved into days, I kept up my Duolingo streak, racking up badges and encouraging notifications from Duo, the brand's green owl mascot. Then came my flight — and with that, the end of my streak.

It didn't take long for Duolingo's emails to shift in tone. One subject line read, "????It's been three days…" The next day, it asked, "Have you already gotten sick of learning Portuguese?" The day after that: "????It looks like you've learned how to say 'quitter' in Portuguese."

I archived the unopened emails without a second thought. After all, I knew perfectly well what I'd signed up for: learning Portuguese from the biggest asshole on the App Store.

Across the internet, nearly a decade's worth of posts, comments, and blogs lament Duolingo's brusque bedside manner, which one Redditor half-jokingly described as an attempt at emotional blackmail to spur reengagement. The nagging goes beyond email subject lines and push notifications; inactive users might look down at their phones to find that the Duolingo app icon suddenly depicts a sadder and older version of the owl's face — or one that's melting into a carnivalesque nightmare. Parents have even complained that the capricious owl is attacking their children's brains and making them cry. Though it's widely accepted that Duolingo can be a real jerk, some have gone so far as to suggest the company's manipulative messaging is flat-out unethical.

For Duolingo, though, the relentless nagging seems to be a boon to its bottom line. Following the first quarter of 2024, the company reported 54% year-over-year growth in daily active users (to over 31 million), 45% growth in revenue, and record profitability. Not too shabby for an app whose affect has been described as "psychotic," "unhinged," and "abusive" — attributes that, if anything, the company appears to be leaning into. Haters may hate Duolingo's scolding, but more often than not, the company's largely under-30 user base laps it up. Love him or loathe him, the owl's got rizz.

It might be an overstatement to call tough love the secret sauce for engaging Gen Z customers. But marketing experts say it's part of the package for Zoomer-marketing magic.

"Younger age groups engaging with marketing are looking for a company that has a special, unique personality that's memorable and feels authentic," said Brian Honigman, a marketing consultant based in Philadelphia. Honigman said that where older adults might respond to corporatized brand messaging — think concise, assertive slogans such as "I'm lovin' it" and "Just do it" — younger adults and teens tend to seek out brands that appear to embody distinct values and interests and have a clear perspective on the world.

"They're looking for something that comes across more like a person," Honigman said. "Duolingo does a fantastic job of not coming across like many other brands."

It might be more accurate to describe what marketers call "authenticity" as "consistency across platforms." No matter the product, marketers tend to agree that a brand's existing customers and potential leads notice when a distinct personality shines through. Regardless of whether people feel warmly toward Duolingo's sassy spokes-owl, they're likely to appreciate that the character holds true to its obnoxious persona beyond the app and user notifications. Throughout its occasional TV ads and regular dispatches on platforms such as YouTube, X, and especially TikTok — where Duolingo boasts more than 12.5 million followers — the smug little bird is uncannily itself.

A recent post on the company's TikTok, captioned "celebrating getting my blue check back," shows Duo twerking, in a purple thong, while being pelted with red roses. A few days earlier, when the pop singer and party-girl paragon Charli XCX announced the release of her new album, "Brat," on X, Duolingo's account reshared the post, adding, "i can't believe u wrote an entire album about me."

Duolingo's brand presence is also irreverently funny in a way that begs to be memed. During this year's Super Bowl, the company went viral for a five-second ad featuring its owl mascot pooping out a miniature of its own face with the caption "Do your Duolingo." The company arranged for users in the US to receive a push notification the moment the commercial aired. "No buts, do a lesson now," it read.

Though the app's reengagement notifications have trended toward bluntness, a Duolingo spokesperson told me the company began leaning into its owl's sassy online persona a few years after an "evil Duolingo owl" meme went viral on Tumblr in 2017. "Since then, we've had numerous social-first marketing campaigns that embrace the meme," the spokesperson said. In 2021, the company released "The Unignorable Notification," a YouTube short in the style of a public-service announcement. It followed that in 2023 with a send-up of personal-injury-attorney TV ads: "Lawyer Fights Duolingo Owl for $2,700,000."

"People love brands with personality," Matt Williams, a visiting clinical professor of marketing at the Raymond A. Mason School of Business at William & Mary, told me. "Too many brands are scared to step out and grab one, but the ones who do it well reap the benefits."

Williams understands this point better than most. From 2013 to 2018, he was the CEO of The Martin Agency, the firm that came up with a cockney-accented gecko to promote the insurance company Geico, which has had a transformative effect on the way insurance companies sell themselves. "I can't tell you how many times, as CEO of the agency that created the Geico gecko, a CMO asked me, 'Can you do for us what you did for Geico?'" he said. "But the downside risk can be just as big. The same influencers that reward Duolingo or Geico when they get it right with an owl or a gecko will take down a brand that gets it wrong." When M&M's transformed its green and brown "spokescandies" in 2022 from sassy characters with high heels to ones wearing sneakers and low heels, critics from all parts of the internet revolted. Conservative critics called it woke; 20-something TikTokers called it a needless crime of "deyassification."

Williams views Duolingo's cheeky owl as a case study in brand personality done right. It struck gold with Gen Z and younger millennial language learners in particular. The company said in a blog post in 2022 that about 60% of the app's US language learners were under 30.

Duolingo's spunkiness isn't just a marketing ploy; it also drives user engagement. Kristen Smirnov, an associate professor of marketing at Whittier College, told me that to keep people engaged, brands tap into their desire to avoid friction. It's part of the formula for keeping people hooked on free-to-play gaming apps, such as "Candy Crush," which make their money selling in-game add-ons and boosters.

"What those designers very deliberately do is they figure out exactly how many moves are likely to be needed in order to regularly solve a particular level," Smirnov said. "And then they offer the player a few less moves." When the player gets tantalizingly close to solving the level, they become willing to pay for the few extra moves needed to win.

Duolingo similarly gamifies friction — not by rigging its challenges but by deploying its trusty sidekick to annoy users. "I am assuming that the company had to ask themselves, 'OK, how do we introduce friction that consumers want to avoid?'" Smirnov said. "So they created that incredibly obnoxious logo, the owl."

Even in a gamified context, emotional friction, such as Duolingo's nagging, can backfire when it's applied over an extended period. Research suggests it's especially risky to deploy marketing campaigns that make people feel bad about themselves; a 2010 study found that the use of guilt and shame in anti-drinking ads triggered a defensive response that actually made their target viewers likelier to drink more. If people feel as though they're constantly bumping up against reminders of their failure, they may decide they're no longer having fun and move on. "People kind of stop treating it like a habit, then they may find that they never open up that app again," Smirnov said, recalling her own disenchantment with Duolingo when she was flooded with notifications after breaking a 52-day German streak while sick.

Despite the research, Duolingo insists its guilt-tripping notifications do the trick of enticing people to drop whatever they're doing to log on to the app. A spokesperson told Debugger in 2020 that "other options" for reengaging users were "between 5% and 8% less effective at getting learners to take a lesson."

Still, not everyone loves it. When Duolingo's head of product, Cem Kansu, posted a thread in 2020 about the success of "the passive aggressive reminder," several unhappy Duolingo users chimed in. "Wow, shame and guilt are how you want to motivate people to learn? that is pretty shitty," one reply said.

But in the grand scheme of marketing, how shitty is it really? Engaging with products and services means opening yourself up to companies' shameless appeals to keep you coming back. It's a dynamic baked into the unspoken contract a consumer tacitly signs when they give their money to a mattress company that promises to give them the best sleep of their life or buy a pair of jeans that evokes effortless French-girl style. Marketing works by appealing to a person's deepest hopes and insecurities, offering consumer goods as the direct gateway to their idealized future self.

Manipulative? Sure. Unethical? Not necessarily.

Mara Einstein, a marketing professor at Queens College and the author of the forthcoming book "Hoodwinked: How Marketers Use the Same Tactics as Cults," told me that ethical lines get crossed when a brand attracts consumers under a false premise or doesn't let them disengage. She cited multilevel-marketing schemes as one example of a business model that routinely draws on both of these unethical tactics to drum up new business. Their approach often relies on bombarding customers with communication and then withholding delivery of the promised goods or services until the customer gives more of their time or money, or both.

"That doesn't happen with Duolingo," Einstein said. "Duolingo may nudge you, but you can always say, 'You know what? This isn't working for me.'" Users can always opt out. (I never did get back to those Portuguese lessons.)

"Ultimately, they're making you feel bad about not finishing your Spanish lessons," said Honigman, the Philadelphia marketing consultant. "At the end of the day, that's not hurting the world."