KUWTK: Kourtney Kardashian Throws a Water Bottle at Kim Kardashian During Expletive-Filled Fight

A fight between the sisters gets shockingly physical in a new promo for season 18, which premieres Thursday

Kim Kardashian West and Kourtney Kardashian are getting physical.

In a sneak peek from the season 18 premiere of Keeping Up with the Kardashians, an argument between Kim, 39, and Kourtney, 40, escalates after the Skims founder implies that her sister isn't a hard worker.

"If I were on my death bed, I would still show up. Mom is so used to me Kourtney ... me and Khloé going on our death beds," Kim says while discussing sister Kylie Jenner possibly missing a runway show after coming down sick. "You don't care about stuff."

The implication that Kourtney doesn't work as hard as her sisters sets the Poosh creator off.

"You act like I don't do s-," she interjects. "You have this narrative in your mind. I will literally f- you up if you mention it again. Literally, shut the f- up."

When Kim starts laughing, Kourtney only becomes angrier.

"But honestly, change the narrative in your mind. I work my f-- a- off," says Kourtney. "I don't want to hear this narrative anymore about this work ethic and 'she's the only one with a work ethic and she's doing this, this and this.' As if she's better because she works more. It's such bulls-. We don't all have to do things the same way."

As Kourtney becomes more worked up, she takes the water bottle in her hand and throws it at Kim.

"But also, if I didn't want to work my a- off and I wanted to be a stay at home mom, that's f-- fine," she says before throwing the drink.

While a fight turning physical is surprising, the drama between Kourtney, Kim and Khloé Kardashian dominated the storyline last season. At the time, Kourtney admitted she had reached her "breaking point" with filming and was thinking about quitting the show.

But she did resume filming, with Kris Jenner explaining on the Ellen DeGeneres Show last month that her eldest daughter "just needed a little bit of a break."

Kris also said that while she wasn't there for the big fight, she told Kourtney and Kim that it was "ridiculous" and to "grow up."

"I have not seen them really fight like that since they were in high school," she said. "It made me really sad. I was like, 'You guys can't be fighting with each other.'"

Keeping Up with the Kardashians returns Thursday at 8 p.m. ET on E!