Kim Kardashian has described the incident where she walked in on then-stepfather Bruce Jenner dressed in women's clothes, years before his transition to a woman.
Appearing on Alec Baldwin's new talk show in the US, Kardashian said she had no idea previously that Jenner had dressed as a woman.
"Nothing. I found out when I was maybe 25 and I walked in on Caitlyn, I mean it was Bruce but dressed up as a woman in the garage at my [mother's] house.
"I ran in and packed a bag so fast, I was shaking and ran out and called Kourtney and said, 'I have to come spend the weekend with you,' and was hysterically crying.
"She was like, 'What is it? Did you catch Bruce cheating?' and I was like, 'I wish. I don't know what I just saw.'
Kardashian told Baldwin Jenner discusses the matter with her but pleaded with her not to tell then-wife, Kris Jenner, because the reality mogul "will kill me".
Kardashian told Baldwin she kept quiet about Jenner's secret for the sake of her younger sisters, Kendall and Kylie.
"I thought, 'OK, if I tell her I'm going to break up their marriage and my little sisters aren't going to have their dad around, so I better keep my mouth shut. I didn't say a word."
Jenner revealed to the world she had transitioned into Caitlyn in 2015 via a Diane Sawyer interview and a Vanity Fair cover story.
Jenner is currently estranged from the Kardashian women, after tensions flared over her memoir, but she still reportedly keeps in contact with her daughters, Kendall and Kylie.
Kardashian also spoke to Baldwin, a staunch critic of Donald Trump, about her husband Kanye West who recently drew criticism for a bizarre meeting with the US President in the Oval Office.
"I let him be who he wants to be," Kardashian said. "I let him have his own views and opinions, even if they're different from mine."
Kardashian said this response came from her childhood. "I grew up in a household where Bruce is my stepdad having one political view and my real father had a different political view, or my mother and we would just always talk about it and be open about it."