Kristen Stewart didn't quite step out in her birthday suit on her born day ... but still left little to the imagination.
She was out with her gf, Stella Maxwell, in New Orleans rocking a crop top -- no bra -- and short shorts. Stella wore pretty much the same kinda outfit.
Kristen just turned 27, and Stella's only 26, but they're already dressing like an old married couple. Works for them ... and for us too.