Kenny is star-struck by the idea of having a flapper in his own front yard, and little wonder.
In the 1920s, independent young women were a novelty, and the flappers symbolized something very new. Just two years after our story takes place, the movie "It" would set a fashion for what "It" was, and the star of that movie, Clara Bow, became known as "The It Girl."
What made the character appealing was that, while she certainly had "It," she was a good girl, a blue-collar, working-class shop girl who helped her unfortunate roommate get by while trying to have a romance with the wealthy son of the owner of a large department store.
In this clip from "It," we see Clara preparing for a dinner at a fancy restaurant, doing her best to keep up with the wealthy, spoiled rich girl who has decided that she should marry the store owner's son.