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Age ain't nothin' but a number -- just ask Hugh Hefner's 24-year-old fiancee, Crystal Harris!

"I don't notice the age difference with Hef at all," Harris tells"Entertainment Tonight" of the couple's 60-year age gap. "If anything, I have to keep up with him!"

"Last year for my birthday I wanted to go bowling," the buxom blonde explains. "And last year for his birthday he wanted to go to Las Vegas and go to two different nightclubs at the Palms!"

Though Playboy editor Hefner, 84, hasn't ruled out having more children with his bride-to-be (he has four kids from previous relationships), Harris isn't necessarily ready for diaper duty.

"Ever since I was little, I always told my mom I didn't want children," she says. "Just animals!"

In the meantime, the recently engaged couple have already begun planning for their low-key nuptials.

"It will be intimate, with a close number of friends, here at the mansion," Hefner says. "No big blowout affair. Something very personal."


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