Playboy magazine founder Hugh Hefner celebrated the holidays with his newest plaything - announcing his engagement to bombshell girlfriend Crystal Harris.

Hefner, 84, said in a Twitter message from the Playboy Mansion in Hollywood that he'd given a ring to Harris, a 24-year-old former Playmate.

Harris, who posed for Playboy in her birthday suit last December, burst into tears at the news that the octogenarian mogul wants to tie the knot, he tweeted.

"This is the happiest Christmas weekend in memory," Hefner wrote.

Hefner later tweeted a second time to let friends and fans know that ring was not simply a Christmas gift for the sexy gal pal.

"Yes, the ring I gave Crystal is an engagement ring," the mogul wrote. "I didn't mean to make a mystery out of it. A very merry Christmas to all."

It would be the third marriage for the still-dapper Hef. He divorced equally stunning Playmate Kimberly Conrad last year. He was married for 10 years to college sweetheart Mildred Williams in the '50s.

Hefner stars in the of E! reality series "The Girls Next Door," which chronicles his life surrounded by 20-something vixens at the Playboy Mansion.

Harris, who studied psychology at San Diego State University, moved into the Playboy Mansion in January 2009 and quickly caught Hefner's eye.

She starred in his reality show along with Hefner's teenage twin girlfriends at the time, Karissa and Kristina Shannon. In October, Harris made a YouTube video in which she tried on various sexy Halloween outfits for Hefner's enjoyment.

An animal rights supporter, Harris described herself to Us magazine as "a good girl, for the most part."