Some stories could involve the idea of transformation. A girl might have chosen a costume that was a bit more revealing than her usual style, like a fairy with a short, flowy skirt. But it was about stepping out of her comfort zone in a safe and respectful environment of Halloween. She got to experience a different side of herself, making friends and having a great time at the party.
I think rather than focusing on the'slutty' aspect, stories could be about how one uses the Halloween spirit to be bold with fashion. Maybe a girl wore a short flapper - style dress inspired by the 1920s for Halloween. She had fun at the party, danced all night, and it was more about the celebration and the unique style she presented, not about being inappropriate.