a fashion accessory that really blows.

by faran krentcil

On their latest catwalk, Topshop brought new meaning to the term "Fashion Police" with outfits inspired by vintage cop uniforms. Many models wore whistle necklaces as part of the looks, which aren't even available to buy just yet. Of course, that hasn't stopped other companies from making the trend blow up. This week, Stella McCartney's luxe whistle necklace hits Net-a-Porter, along with versions from ASOS and Agent Provocateur. And the ones from Falling Whistles raise money to aid war refugees from the Congo. (There's also the one Justin Bieber wore that's covered in diamonds and worth $35k. But we try not to think about it...) We've rounded up our favorite whistle necklaces below. We considered listing all the potential headlines for this story, too, but a bullet-point sheet with "Blow Me," "Blow Hard," and "Blow Up" didn't seem as funny in print as it did in our office...

Stella McCartney Whistle, $425.

A whistle on the Topshop Fall 2012 runway.

River Island Necklace, $5.

Falling Whistles necklace, $34.

Heart whistle, $18

Wood whistle, $11</

Titanic whistle, $

Corona whistle, $16