Kim Kardashian 's feud with Kourtney Kardashian is so last season. Now, the SKIMS designer is sparring with younger sis Khloe Kardashian , who she called out for having a "stick up" her "ass" in the season five premiere of The Kardashians . (For a breakdown of all the must-see Kardashians moments, watch Kards Katch Up here .

) As seen in Hulu's May 23 episode, their beef started in September when Kim decided to fly to Paris for 12 hours to support Victoria Beckham 's fashion show . And although she invited Khloe to come along, it was a hard pass for the Good American founder. "There are a couple things that are holding me back from wanting to go to Paris," Khloe explained in a confessional, pointing to her kids' school routine and the final weeks of Kourtney's pregnancy with baby Rocky .

"I feel like someone has to be here, even for all the kids. Like, God forbid there is a natural disaster, I just feel like somebody has to be here. I know I'm an over-thinker.

I know I'm insane. Welcome to my mind." It's just one of the differences that Khloe—who shares kids True , 6, and Tatum , 21 months, with ex Tristan Thompson —sees between her and Kim.

"Kim can fly by the seat of her pants, but I'm not gonna change who I am," she added. "I was like, ‘You know what? I actually don't care to do this.' I would rather be with my kids.

" Kim, on the other hand, doesn't see a problem with her workaholic ways—which included flying to New York for six hours before her whirlwind Paris Fash.