Kelly Clarkson and Keke Palmer definitely are no scrubs when it comes to covering a classic hit.

The duo spontaneously busted out a version of the 1999 TLC smash “No Scrubs” when Palmer stopped by “The Kelly Clarkson Show” in a clip posted to the show’s YouTube channel on Jan. 22.

Here’s how it went down: The pair competed in a game called “Pop Pop Quiz,” hosted by “American Ninja Warrior” announcer Matt Iseman, in which the answers to questions about certain songs were contained in the respective songs’ lyrics. The score was tied when the final question came up.

“Out of which side of the car was the ‘scrub’ leaning while he tried to holler at TLC?” Iseman asked.

“Passenger side of my best friend’s ride!” Palmer answered before Iseman could even finishing reading the question.

The audience was still applauding her answer when she had a microphone in her hand, singing “No Scrubs,” as Clarkson, also holding a microphone, joined in, covering the hit that made it to No. 1 on the Billboard Hot 100.

The pair belted out the track, while Iseman danced along and the audience stood on its feet, also moving along to the performance.

Kelly Clarkson and Keke Palmer do impromptu duet.
Keke Palmer (left) and Kelly Clarkson (right) perform “No Scrubs” while Matt Iseman (center) soaks it in.YouTube
After they wrapped up, the crowd continued to thunderously applaud, while Clarkson jokingly questioned how the “Nope” star, 31, could like the song so much.

“She’s been up here hollering about her age, and that song is not your age bracket,” Clarkson teased.

“I remember being in the second grade performing this at my little school’s talent show,” Palmer quipped. “Yes I did. And I played Chilli in a movie,” she said, referring to when she played TLC member Rozonda “Chilli” Thomas in the 2013 TV-movie “CrazySexyCool: The TLC Story.”

Fans watching the duet on YouTube were blown away by Palmer and Clarkson’s effort.

Kelly Clarkson and Keke Palmer do impromptu duet.
Keke Palmer (left), Matt Iseman (center) and Kelly Clarkson (right) had themselves a good time.YouTube
“That no scrubs harmony was PERFECTION,” one fan commented.

“Alright now Keke!! You betta SANNNG girl!!!” another person wrote. “Okay sooooo, I’m gonna need a full on version of these two singing No Scrubs!! Kelly’s harmonies as always were perfectly on point, showing us yet again that she can literally sing with ANYBODY, and why SHE is the OG American Idol!!!”

“Them not making an R&B collab together some day will be a crime against humanity,” someone else raved.

“Woooow they ate that performance doooown i replayed it twice they have such great chemistry,” another user cheered.

Palmer now finds herself in pretty good company by joining a long list of artists who’ve performed with Clarkson on her show, which includes but isn’t limited to Jelly Roll, Miranda Lambert, Weezer, Alanis Morissette, Babyface and Pink.