PS2 Black Cheats

[Lawrence]

Unlock the BFG for Veblensk City:
Enter the password as your profile name, including the hyphens.

Unlocks BFG for Veblensk City - 4SUD-A2DX-8EBU-KFFX

BFG Code:
Enter the following code to enable access to the BFG.

Unlocks BFG - FG6S-WFZG-7MDP-PZGT

City Streets level-Unlock BFG (M249 Machine Gun) Cheat:
Enter any of the following codes as your profile name. Make sure you include the - symbol when entering the code (it's next to the ! symbol). After entering the code and clicking "Done", you'll be able to enter your real profile name. This is how you know the code was accepted. When you begin the first level, you'll have an M249 machine gun instead of your normal gun.

Unlocks BFG gun for City Streets level - EG4P-ZGUJ-6SQJ-3X68
Unlocks BFG gun for City Streets level - HQ6G-ZP3B-C5LE-WMXA
Unlocks BFG gun for City Streets level - 5SQQ-STHA-ZFFV-7XEV

Unlockables:
By completing the game on the various difficulty settings, you will unlock a certain reward.
Silver Weapons (unlimited ammo) Complete the game on either the Normal or Hard difficulty setting to unlock them for that difficulty level.

Black Ops difficulty setting - Complete the game on the Hard difficulty setting.
Have M16A2-All Levels - Complete the game on the Black Ops difficulty setting. The M16A2 can be used on any difficulty setting once unlocked.

Source