While playing a game, press R, Black, L, Black, Left, Down, Right, Up, Left, Down, Right, Up. A note will confirm that you entered the code correctly. The least powerful weapons in each category and rocket launcher will be unlocked. To get infinite ammunition for this or the other weapons tiers, repeatedly enable the code until no ammunition number appears beneath the gun pictures. Enabling this code will cause your street creds to drop in points. You can check your creds in the stats menu at the pause screen. If you are in the negative, you are a Playa-Hater.