@krisjenner / Instagram 1 / 5
@krisjenner / Instagram 1 / 5

Although over-sharing is expected with the Kardashian/Jenner family, Kris Jenner recently spilled pretty humiliating details of the most embarrassing event in her life.

"The most embarrassing moment for me was when I was with [Caitlyn Jenner, who was formerly Bruce Jenner] on a commercial airliner in first class. We joined the Mile High club," the 59-year-old confessed to "Cosmopolitan."

"We felt we got away with it. We had sex in the bathroom and we came out and nobody said anything," she revealed in a behind-the-scenes video from the magazine's 50th anniversary cover shoot.

But that wasn't the humiliating part for the mother of six.

"At the end of the flight, the flight attendant got on the microphone. 'Congratulations, Mr. and Mrs. Jenner! You've just joined the mile-high club. We're so proud of you, and we decided to give you a bottle of champagne! Yay!' I could not squish down in my seat low enough. I was mortified!" she cringed about the incident, which took place on an American Airlines flight before Kendall and Kylie Jenner were born.

Kris and her five daughters will appear on the front cover of the "Cosmopolitan" anniversary issue. The magazine dedicates 16 pages to the reality family.

"Happy 50th birthday @cosmopolitan!!!" Kris posted on Instagram. "So honored to be on the November cover with my girls!!"

The issue hits newsstands on Oct. 13.