The 23-year-old model and her 40-year-old half-sister have been spending more time together lately, and earlier this year Kourtney even tagged along on a ski trip to Mammoth, California, with Kendall and her friends.
But in a preview clip for this week's episode of 'Keeping Up with the Kardashians', Kendall is seen admitting she didn't enjoy the trip because Kourtney was ''a bit rude'' to her in an effort to get closer to Kendall's pals.
She fumed to Khloé Kardashian: ''You know, Kourtney and I have been getting a bit closer over the past couple of years and I love that she hangs out with me and my friends. But to be honest, I felt like there were just some moments where she was a bit rude and it really started to get to me at a certain point.
''A lot of the trip, people were picking on me, and by people I mean Kourtney, most of the time. Whether she thought she was joking, I didn't really think it was a joke. I just felt like she was trying to be cool in front of my friends and like, younger people that are cool, at my expense.''
Kendall then went on to complain about a time in which Kourtney had refused to listen to her about not putting her feet up on the centre console of Kendall's car.
She continued: ''Mind you, it's like, rainy and muddy outside,'' she explains. ''I go, 'Kourt, can you not put your feet up on my thing?' And she goes, 'Kendall, it's a f***ing vehicle.' I go, 'So? I don't want your shoes all over my car.' And she goes and puts her feet onto the [headrests].''
To which Khloe, 34, replied: ''That's so rude.''
And the model shared another example in which Kourtney got all of Kendall's friends to ''laugh'' at her when she asked her friend Fai Khadra to keep her car keys on him while they went skiing.
Kendall said: ''I was like, 'Are you sure you have a zip pocket? I don't want it to fall out.' ... I mean, literally, how would we get home if we lost the key? And Kourtney goes, 'Kendall, chill the f**k out, it's a key.' And then my friends, all of them laugh with her. None of them took my side, they're all just laughing together. And then she feels that validation.
''I'm not blaming my friends at all. They're not doing it because they're trying to be mean.''
Khloe took Kendall's side in the discussion, as she later said she was disappointed in Kourtney for ''bullying'' her younger sister.
She said: ''She's supposed to be the older sister, but it just seems like Kourtney was bullying Kendall the entire time. I mean, that's so lame for anyone to do that.''
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