KRIS JENNER has been caught in a big fat cheating lie!

The reality TV “momager” proudly proclaimed on “Keeping Up with the Kardashians” that she’d passed a poly­graph test about cheating on hubby Bruce with a former flame.

But the test was blasted as “flawed” by the ex­pert who conducted it, and insiders say the whole scenario was cooked up to goose the show’s rat­ings!

“Kris did not pass the polygraph!” polygrapher Joe Paolella, who administered it, told The EN­QUIRER. “The test was flawed from the beginning, and while Kris maintained she passed it, the test was inconclusive at best.”

An insider added: “The whole lie detector scenario was a setup! Kris snuck off to meet her ex-flame, Todd Waterman, but decided after the rendezvous that it was a mistake.

“When she came clean to the family, they were out­raged, so she agreed to a polygraph. But it was all a bunch of bull, and the whole family, including Bruce, was in on it!”

On the July 29th ep, Kris reunited with her old flame Todd – the man who came between her and her late husband, attorney Robert Kardashian.

Kris, 56, claimed that she’d met Todd only to get “closure,” but when she told Bruce, he hit the roof.

Daughter Kourtney suggested Kris take a lie detector test to prove her love for Bruce, and Paolella – who’s administered more than 16,000 polygraphs – was asked to conduct it.

“I was contacted by an agent, but I wasn’t told who the examination was for,” said Paolella, a for­mer Secret Service agent who served under four presidents while assigned to the White House Protective Service Detail.

“The Kardashian girls called me to discuss the questions, but I didn’t know who they were until I arrived to conduct the test.

“Kim met me at the door and escorted me to the  kitchen. I was told where to set up and Kris came in soon after. Before taping started, I explained that no one else should be in the room during the polygraph, and that it needed to be done twice so the two tests could be compared for accuracy.

“But Kris and her daughters told me it wasn’t a big deal, and just do the best I could.”

Paolella conducted only one test on Kris. When he asked whether she wanted to have an affair with Todd, she said “no” – and the polygraph needle went crazy!

“Obviously, the extreme needle movement im­plied Kris was lying and was still considering having an affair with Todd,” said the source.

“On the show, Bruce stormed out of the kitchen. But the whole idea was to deceive the viewers, not Bruce. He was in on the whole thing!”