This is the Black Bowtie, which used to be found in the F.I.S.H. ( Factual Informative Spy Handbook ), which only costs 50 coins. It was also available during Club Penguin's Server Testing 2005. It is a secret item when it was released in the Penguin Style. Penguins can obtain it by uploading coins to their online account using the D.S. game: Club Penguin Elite Force. If you wear it with the Conductor's Suit, you'll do a special dance, too!
Credits to Patzi3 for the picture.