Crystal Harris and Hugh Hefner

Did anyone ever tell Crystal Harris it's not polite to kiss and tell?

Harris, 24, who was thisclose to marrying Hugh Hefner, is now dishing on their sex life. In an interview on Howard Stern's Sirius XM Radio show, she said sex with Hef lasted "like two seconds."

Hugh Hefner's Lifetime wedding special to air as "runaway bride" theme

"Then I was just over it," she continued. "I was like, 'Ahhh.' I was over it. I just like, walked away. I'm not turned on by Hef, sorry."

Harris called off the wedding just five days before they were set to walk down the aisle. Hefner, the 85-year-old Playboy founder who's been married twice before, proposed to Harris on Christmas Eve.

Why Crystal Harris called off wedding to Hugh Hefner: "This isn't the lifestyle for me"

"I called it off because I didn't think it was the right thing for me to do," she said On-Air with Ryan Seacrest the morning after canceling their nuptials.  "Hef's lifestyle isn't the most normal lifestyle. This isn't the lifestyle for me, multiple girls all around. It's not the lifestyle I wanted."

It didn't take Hef long to move on. He already has two new girlfriends, which sparked Harris to tweet, "I was replaced the day after I left. #expected."

See what Harris told us when she came to the studio Tuesday: