One can't dress as one of the great iconic biker girls of the 1950's without having the right hair. In fact, no matter what decade that's contributing to your costume if you don't get the hair right, it's hardly a costume at all.
That's why you need the Pinky Tuscadero Wig - Happy Days. And even if you aren't a massive fan of Happy Days or Pinky Tuscadero, this wig can still be used in any number of ways, from biker girls to betties. As I'm sure you're aware, the 50's lasted for an entire decade and your options are as large as the decade that Ike built.