Well, suffice to say, Halloween is basically an excuse for those kinds of girls to dress that way. To paraphrase the entire sequence, the only girl who never heard of it actually had a proper Halloween costume, complete with fake blood and makeup that makes you look like a corpse, and everyone stared at her like she was crazy... all while the other girls had the routine cat ears and skimpy clothing.
That said, I still don't find these half as mortifying as the Muppet character TONGUE STUDS that they once sold... especially after hearing a Chris Rock monologue.
(Waits for the day they release sexy costumes designed after Bulma from when she first appeared in Dragon Ball.... now that I would like to see.)