In his new tell-all book, Prisoner of X, former Hustler editor Allan MacDonell tells the story of how he claims to have bluffed House Speaker-elect Bob Livingston into believing Hustler had something about an extra-marital affair.

The hoax stemmed from a notorious publicity stunt that smut-raker-turned-political-muckraker Flynt pulled when he took out a Washington Post ad in which he offered $1 million or more to anyone who could provide evidence of “sexual indiscretions” by top Republican officials in the wake of the Monica Lewinsky affair.

In 1998, Livingston, a Louisiana Republican and avid proponent of impeaching Clinton, got snared in the Hustler hoax. “We actually had nothing on Livingston,” MacDonell tells Page Six. He explains, “an elected Republican office holder from Louisiana passed us the phone number of a woman who was supposedly Livingston’s girlfriend. But when we phoned her, she cursed us and hung up.

“About a day later,” MacDonell says, “a reporter from Roll Call [the Capitol Hill newspaper] called and said he’d heard that we were working up something on Livingston. I thought: What would Larry do? Then I said, ‘I cannot discuss any names or other details at this time.’ The reporter replied: ‘I’m running with it.’ ”

MacDonell, 50, says that after a news-show interview the next day – in which he claimed that Hustler was investigating Livingston’s sex life – “within 24 hours, the Speaker-elect quit Congress.” Chuckles MacDonell – who was fired for cutting remarks he once made about thin-skinned Flynt during a celebrity roast – “Clinton should have put me on his Christmas-card list for life.”