Christina Aguilera Shares nude picture, Says She Used to Be Dirrty And She Still Can Be

Just when you thought Christina Aguilera's days of showing off her tiny physique were behind her -- the 34-year-old mother of two flashed almost ALL of her still hot bod with a topless photo.

Sporting just pink panties in the pic ... Xtina captioned it,

  "Felt like it was time to start sharing some personal stuff with you guys."

If this is what she has in mind ... we couldn't agree more.