Kourtney (43) and Khloé Kardashian (38) underwent a lie detector test for "Vanity Fair". In a 14-minute YouTube video, the sisters ask each other questions and bring one or two explosive details to light. Above all, Khloé can't resist one or two digs at Kourtney.

When asked about her sister's wedding dress, Khloé replies that she thought it was "okay," adding, "I mean, it was definitely beautiful. I would have liked it better if you'd worn it to the after party, and before that something else." When asked if she would let her daughter True, 4, stay with Kourtney, Khloé replied, "Probably not."

Kourtney also asked her sister if she would still sleep with her ex-partner Tristan Thompson (31), who had cheated on her several times. Khloé's response: "No, I don't. I really don't." Confirmed as truth by the lie detector, the 38-year-old can breathe a sigh of relief: "I would have died if it had said I was lying."

In her question and answer session, Kourtney Kardashian also announced an explosive detail from her relationship with Travis Barker (47), which had previously been rumored to be circulating on the internet. "Do you have a foot fetish?" Khloé asks her sister. "I personally don't," she replies. "Does Travis have a foot fetish for your feet," Khloé asks. "Yes, possibly. Yes, yes," said Kourtney.