At the start of the night's episode, Kim was chilling out with Kendall Jenner and Scott Disick around her kitchen table, and Scott asked her about the high school reunion she recently went on, which was featured during last week's episode.
While Kim said she rented out a party bus and hung out with a bunch of her old besties, it sounded like she still had a rather responsible (some might say tame) night out. This was something Scott had a hard time abiding without chiding her a bit.
"You were fun, right? At one time?" Scott asked, sarcastically. "You were, like, wild during some of your years, right?"
As it turns out, yes she was. While Kendall said that she'd "heard stories" about some of Kim's wilder adventures, the 23-year-old runway model admitted to her big sister, "I didn't know you got high."
"You were high on ecstasy when you did that sex tape?" Scott asked, somewhat shocked.
"Absolutely! Everybody knows it. My jaw was shaking the whole time," Kim said, explaining that she would frantically grind her teeth side to side while on the drug.
Kim also shared a story about how she and her longtime friend Paris Hilton once partied in Ibiza until the wee hours of the morning before Kim convinced her socialite bestie that it would be a good idea to sleep on some buoys in the ocean, which they apparently did.
Even still, Kendall said she had a hard time wrapping her head around the idea of her sister being a wild party girl.
"Kendall, honestly, has no clue," Kim said in a solo interview with the KUWTK cameras. "I definitely went through a wild phase in my late teens. I'm not like that anymore."
"But I still have fun!" she added. "Don't get it twisted, I'm always the life of the party."