Valley Girl 
noun US informal
A fashionable and affluent teenage girl from the San Fernando valley in southern California: Sloane Rangers and Valley Girls have slang [as modifier]: the surfers, Valley Girl accents and hustling gurus...
- She adopted a Valley Girl persona, and didn't seem comfortable playing a character that was supposed to be a version of herself.
- From everything I've read, I was expecting a doltish, giggling Valley Girl.
- Only by adopting their lilting, Valley Girl voice inflections can one gain their growing approval and, ultimately, an invitation to join them at a party.