Kylie Jenner and Rosalia went viral, but they had no idea about it until months later.

The entertainers posted an innocent clip of them screaming in excitement when Rosalia joined Jenner in her daughter Stormi Webster's second birthday bash in February 2020. It wasn't the only video from the day to make the news, though, because it was about the Kardashians.

But, their screaming clip hadn't gone viral until now, two years later. The video with their screams made for perfect voiceover sounds for many creators on TikTok, which started a trend of similar content on the video-sharing platform.

The trend started in November, but it wasn't until two months after that Jenner and Rosalia noticed the popularity their high-pitched noise had gained.

About ‘Baby Girl’ Ft. Kylie Jenner Trend

The first time Jenner and Rosalia's clip was used in a TikTok was in November 2021. A creator that goes by cxaluv on the platform used the clip at the start of her video, posted in November 2021.

One of the original versions, posted on November 16, transitioned from playing the screams to a montage of Alana Rose's (@_lustforlana) pictures. Aaliyah's 1998 collaboration with Timbaland, 'Are You That Somebody,' played as the montage track.

"an absolute queen," the caption of the post read as it tagged Rose's now-deleted account. Aaliyah's song was remixed and renamed as "yeah hot people use this sound - cxaluv" on the post.

This particular video, which has 1.2 million likes as of this writing, along with a few others, started the trend, and the tune became a big thing quickly.

As for how the trend got the 'Baby Girl' name, it is thanks to the A-listers who caught the wave of the tune's popularity. Celebrities like Cara Delevingne, K-Pop band P1Harmony, and Noor Dabash have all made their own versions of this, all of which include Jenner and Rosalia's high-pitched screams at the start.

Delevingne posted her TikTok using the same tune with the caption "Baby girl..." on December 1, 2021. Dabash did the same alongside Nic Kaufmann on December 2, and P1Harmony uploaded theirs on December 23.

The trend also got into the Kardashian household.

Jenner's niece, Kim Kardashian's daughter North West (username - @kimandnorth), did a TikTok using the sound piece on December 16 with the caption, "Pajama day at school." She was wearing red pajamas and a white beanie.

Similarly, her other niece, Khloe Kardashian's daughter Penelope Disick (username - pandkourt), also created her own thing with the tune.

Her video, uploaded on December 7, first showed her lip-syncing Jenner's scream with a face mask, then transitioned to a mirror selfie video where she lip-synced to Aaliyah's lyrics.

When Kylie Jenner and Rosalia Caught Up

Between the two entertainers, Jenner was the first to become aware of her scream going viral. At the beginning of January 2022, Jenner reshared a fan's post on Instagram stories, which included the now-famous screams.

Kylie Jenner and Rosalia show their surprise to a sound clip of them screaming going viral on TikTok.

Kylie Jenner and Rosalia show their surprise to a sound clip of them screaming going viral on TikTok. (Photo: Rosalia/Instagram)

The model tagged Rosalia, writing "omg" and using laugh-cry emojis to express her feelings about the trend.

Rosalia soon reposted Jenner's story on her own and wrote, "queeeeeeeee" (Spanish for 'what') with four laugh-cry emojis.