The trendy short-form mobile video sharing app is wildly popular with Gen Z and has helped launch everything from hit songs to viral tees.

If you’re over the age of 22, you’ve probably never used – let alone heard of – TikTok, but the short-form mobile video sharing app is a massive platform that just hit 1.5 billion downloads and has 1 billion active users. More importantly for the promo world, it’s a breeding ground for youth culture, where viral memes and fresh slang are born with every 15-second lip sync clip posted. And for print-on-demand e-commerce vendors, it can be a great way to find fodder for the latest moment merch.

Jonathan Garriss, CEO of novelty merch maker Gotham City Online, recently told CNBC that his staff frequents places like TikTok and Reddit for trending memes, since social media sites that skew older, like Facebook, tend to be outdated. “We try to find memes that have a little more staying power,” he said. “There are things that are popular this week and not popular the next. We try to avoid those.”

Print-on-demand vendors are finding inspiration from 15-second videos on TikTok. Photo via Amazon.

Gotham City Online sells T-shirts on Amazon through its subsidiary Pop Threads. Amazon’s print-on-demand services make it easy for Gotham City Online to experiment with designs and memes to see what sticks. “If we create a design that doesn’t work, it’s not like we’ve got a thousand shirts sitting on the shelves. We produce them as they start to sell,” Garriss told CNBC.

Here’s a sampling of the internet slang that’s been memorialized in thread and ink: “Respect the drip, Karen,” which references a TikTok video of a teen telling his stepmom to respect his outfit; “Yeet,” an expression of excitement, approval or surprise; and “OK boomer,” Gen Z’s dismissive, sarcastic response to criticism from older generations.

Celebrity Kylie Jenner capitalized on a TikTok meme she inspired by selling hoodies in her official shop. Photo via The Kylie Shop.

TikTok also has star-making power. The biggest success story is rapper Lil Nas X, who uploaded his award-winning, genre-defying country rap hit “Old Town Road” to TikTok late last year, turning it into a meme and propelling the song to a record 19 weeks at number one on the Billboard charts.

Another example occurred in October. Kylie Jenner posted an office-tour video on YouTube, at the end of which she sang the words “rise and shine” to her sleeping daughter, Stormi. In less than two weeks, the impromptu serenade had become a massive meme on TikTok. In grand Kardashian tradition, Jenner wasted no time merchandising the clip, posting hoodies based on the meme onto her online shop. She also applied for a trademark on the three-word phrase.

The runaway success of TikTok has certainly caught the attention of other social media sites – including Facebook, which has been testing Reels, a copycat video-editing tool for Instagram, to try and steal some of TikTok’s thunder. While the typical TikTok user doesn’t match the typical demographic of a corporate buyer (according to GlobalWebIndex, 41% of users are between 16 and 24 years old), it mirrors the trend of past successful social media sites that started young before capturing older demographics. In addition, it heralds a movement toward bite-sized video that could prompt promo professionals to keep their marketing messages short, sweet and set to a catchy beat.