What code is everybody talking about?
It’s a redeemable code on Xbox Live called Specialization Priority Alpha. The code, once redeemed, gives you all of the Halo 4 Specializations unlocked for multiplayer. The code was supposed to be received by everyone by Monday for all players who met certain requirements to receive the code, but basically there was a lack of communication and poor management of the distribution of the codes and many players, including myself, have yet to receive the code.
It was originally sent in an e-mail to the e-mail address associated with your Xbox Live Account. Check to see if you have it.