Christina Aguilera's Getting All Dirrty Again

Hey, so Christina Aguilera wanted to get personal -- her words, not ours -- with her fans ... and what better way to do it than to pull a Kim Kardashian, posing topless and in underpants?

It's been a minute or so since Christina's made real waves ... unlike her contemporaries, Britney Spears and Lindsay Lohan and of that ilk ... so instead of saying "it's about time" (because this is just silliness ... acting like photos like this are some kind of "treat" to fans), we're just gonna go ahead and say "it was only a matter of time."