Xtina to Pose for Playboy?

Christina Aguilera's been singing about being "dirrty" since her 2002 smash hit, and it seems someone was listening. Hugh Hefner has approached Xtina, 27, to pose for Playboy magazine, a source tells OK!

"Hef has always loved Christina," the insider says. "He finds her Old Hollywood glamour stunning and magnetic."

Is the mom of 6-week-old Max going to reveal all for Hef? A pal of the singer tells OK!, "That was old Christina. That was Christina circa four years ago. She's looking to reinvent herself and grow. She wouldn't consider it but she finds it flattering to be offered at all."

Christina's rep tells OK!, "The reports are false."