It's the JammyPack, and it's pretty cool.
Outfitted with 8-watt internal drivers and two 3-watt speakers, these fanny packs run off either disposable AAs or a rechargeable battery pack that lasts 4x longer than an iPhone ($40). Choose from a dozen color schemes.
If you want to carry more stuff to your portable party, opt instead for the Hoarder Backpack, a messenger-style slingbag with more cargo space and an 18-watt driver. It actually has a good amount of room.
Features:
It's the JammyPack - give it a look.