Gearbox is getting into the Halloween spirit by giving away skins for Borderlands 2. On October 31, Gearbox will give out SHiFT codes on Twitter and Facebook that will unlock special Halloween skins for Borderlands 2 classes. The giveaway will begin at 10am Central, and it will continue throughout the day. The codes will expire at 11:55pm Central on November 4.
Gearbox frequently uses SHiFT codes to give away golden keys for Borderlands 2. The codes can be redeemed once per account. Unlike other redemption codes, SHiFT codes are not limited to a single person with fast fingers. They’re more like gifts to the community.
SHiFT codes can be redeemed by going into the Extras menu within Borderlands 2.
Source [Gearbox Software]