Does that emoji look familiar? Kourtney Kardashian opens up about her heated conversation with brother Rob over Blac Chyna's ChyMoji app in Keeping Up With the Kardashians' Sunday, August 21, episode.

The E! series' sneak peek shows Kourtney, 37, telling pal Mario Dedivanovic that she wasn't pleased to see an emoji on the app of a Kylie Jenner look-alike getting slapped. Jenner, 19, and Chyna, 28, have had friction between them, stemming from the KUWTK star dating Chyna's ex-fiancé, Tyga, who shares 3-year-old son King Cairo with the model.

"This was the first time that made me question Chyna's intentions," Kourtney tells the camera about her brother's pregnant fiancée. "Like, I usually don't let any of this stuff bother me, but for some reason this just sets me off."

Kourtney reveals that Jenner suggested she contact Rob, 29. But when the mom of three reached out to the sock designer, he lost control and threatened to disparage the family at a public event.

"I went off on him yesterday," Kourtney tells Dedivanovic. "He's like, 'I'm going to go on the red carpet tonight, and I'm going to tell everybody how I have the worst, most unsupportive, disgusting family.' Like, ridiculous. But I think it's stupid to take it there."

Jenner and Chyna had appeared to put their tension aside in April when the Lip Kit by Kylie creator shared a pic to Snapchat of them hanging out, and referred to the pair as "best friends."

Watch the clip in the video above. 

Keeping Up With the Kardashians airs on E! Sundays at 9 p.m. ET.  

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