The Surprising Reason Kendall Jenner is Angry With Kourtney Kardashian in the New 'KUWTK' Clip

The preview for this week's episode of Keeping Up With the Kardashians shows a very upset Kendall Jenner. The target of this anger? Her oldest sister, Kourtney Kardashian.

In a new clip from E!, Kendall speaks with Khloé about how hurt she feels, explaining that she recently went to Mammoth on a ski trip with friends and Kourtney tagged along. Although it might've sounded like a good idea at first to the 23-year-old model, the mood quickly changed when Kourt apparently started picking on Kendall.

In a confessional, Kendall says:

"This past weekend, Kourtney came with me and my friends on a ski trip. You know, Kourtney and I have been getting a bit closer over the past couple 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."

Kendall speculated that Kourtney was trying to impress her friends without considering her feelings. The star says in the clip that Kourtney put her muddy feet all over her car and later, when Kendall was trying to assure she had a safe place to keep her keys while they were skiing, Kourtney yelled at her to "chill the f**k out."

To make matters worse, Kendall's friends all laughed with Kourtney. The clip also shows Khloé mulling the matter over. "I'm so annoyed with Kourtney," she says in a confessional. "She is supposed to be the older sister, but it just seems like Kourtney was bullying Kendall the entire time."

To find out of Kendall and Kourtney can get through their beef, catch KUWTK this Sunday on E!