Kim Kardashian and Kourtney Kardashian dropped a surprising revelation about the activities they liked to do as teenagers.

During a new episode of The Kardashians, which started streaming on Thursday, October 5, Khloé Kardashian outed her older sisters while at Century City mall.

“This mall has been around for years. You should ask Kourtney and Kim, they used to call 900 numbers [premium rate telephone numbers] and ask gentlemen to meet them here,” Khloé, 39, shared with the cameras while filming at the location of her new Good American store.

In a confessional, Kim, 42, broke down her and Kourtney’s strategy. “We would talk to these guys — we were 15 — and then they would be like, ‘Meet me at Blockbuster or at the mall.’ And we would see the poor guy and we would stand him up,” she admitted. “We would take a Polaroid, I have a book of Polaroids of these guys that we would stand up at the mall.”

The Skims founder called Kourtney, 44, to see whether she memorized the number they used. After Kourtney confirmed she still knew the number “by heart,” Kim called in while filming her hit Hulu reality series.

The automatic message for the service stated, “This is [redacted], where naughty is nice. Your live chat starts now.”

Viewers got a chance to see Kim talking to an unknown guy before hanging up. “Hi, this is Samantha. What’s your name? Where do you live? I stay in Ventura County,” she said and then promptly ended the call. “I can’t. I got to save that number in my phone.”

Kim and Kourtney’s blast from the past comes after a blowout between the sisters aired in the season 4 premiere. The feud initially started one season prior when Kourtney accused Kim of using her wedding to Travis Barker as a business opportunity. Their issues progressed after watching confessionals from season 3.

“The problem is — and I will be real with you guys — last season was really rough. Then we were over it, we had fun. We talked it out [and] everything had been fine,” Kim explained to the cameras in a September episode. “Then we watched the edits for our show and I start hearing what she is saying about me. She hears what I am saying about her and then we get mad all over again. It brings up so many feelings.”

The episode also featured a tense conversation between Kim and Kourtney where they addressed their distance.

“I see both sides. I think you think things so you are getting riled up. I think things so I am getting riled up,” Kim told Kourtney. “That is totally your choice and your decision. I just think we should have a conversation about it. I got worked up when I was like, ‘Wait, nothing happened at the wedding. There wasn’t even a conversation at the wedding.’”

As the discussion got more heated, Kourtney claimed Kim’s behavior caused their current divide.

“You are talking about the bulls—t details because it is all your egotistical selfish mind can think about,” Kourtney said. “You cannot stand someone else being the center of attention. You came to my wedding [and] you couldn’t be happy. You complained from the second you got there until the second you left. That is what it is about. Forget that you couldn’t be happy, you couldn’t be happy for me. You couldn’t be happy that I was the center of attention and you weren’t.”

Kim, however, wasn’t going to take the blame. “What is it that you feel so low [about] me? I want you to dig deep and figure out why you hate me so much and why you are so angry with me. Because all of this never happened. I was so happy for you,” she retorted. “Why would I not be happy for you? Because you have a serious vendetta. You just hate us. You are a different person and we all talk about it.”

After Kim alleged that Kourtney’s loved ones were concerned about her, the Poosh founder broke into tears. “Get a f—king life. I don’t have side chats about anybody,” she said. “Is that helpful? You’re like adding it into the fight so it is you and my friends and my kids and everyone against me. You are just a f—king witch and I f—king hate you.”

Kourtney continued: “There are so many thoughts that come up after watching the edits. I think to me it felt on the call like Kim was just using any weapon that she could find to hurt me. [It felt like she was] weaponizing everyone against me and we both got to a place we weren’t proud of.”

Portions of the phone call went viral after the season 4 premiere aired. In response, Kourtney offered a glimpse at her group chat where her friends confirmed they weren’t on another text chat with her family.

“These trolls keep DM’ing me, accusing me of being in the other chat,” Simon Huck wrote before adding, “Kim threw us all under the bus when there was not one actual friend on the chat.”

Hulu releases new episodes of The Kardashians every Thursday.