Even Khloe is "annoyed" with her sister when she hears this.
In a clip from Sunday's new episode of "Keeping Up with the Kardashians," Kendall vented some major frustrations to Khloe after their vacation left a bad taste in her mouth.
"We went to Mammoth. To be honest, it was kind of a lot for me," said Kendall. "A lot of the trip, people were picking on me -- and by people, I mean Kourtney most of the time. Whether or not she thought she was joking, I didn't really think it was a joke."
In a confessional, Jenner said that while she loves how close she and Kourtney have become, Kardashian was out of line on their trip.
"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," she explained.
Speaking to Khloe, she elaborated.
"I just felt like she was trying to be cool in front of my friends and younger people that are cool ... at my expense," Kendall said.
Giving examples of her sister's behavior, she said Kourtney snapped at her when Kendall complained about her muddying up her car. "Kendall, it's a f--king vehicle," she apparently said.
Kourtney also told her sister to "chill the f--k out" at one point as well. "She was like putting me down to make herself feel higher or cooler," Kendall added.
After hearing Kendall's complaints, Khloe said she was "so annoyed with Kourtney" as well in a confessional. "She is supposed to be the older sister, but it just seems like Kourtney was bullying Kendall the entire time."
A fight between Kendall and Kourtney has been teased for the upcoming episode of "Keeping Up with the Kardashians," which airs Sunday on E!