Painting your nails didn't go quite as expected, and the proof is there for all to see--a glaring nail-polish stain jumping out at you from the grout between the tiles.
How you got a stain there doesn't matter; how you're going to get rid of it does. Though this may seem like a dismal task, you'll be pleasantly surprised at how little time and effort this should take.
Soak a paper towel in non-acetone nail polish remover.
Place the paper towel on the grout and press it down firmly so it's making contact with the entire stain.
Leave the paper towel on the grout for three to five minutes to soften the nail polish.
Dip an old toothbrush in the nail polish remover and gently scrub the area until the stain is gone.
Rinse the area with clean water.