when your playing black-ops campaign when your intaragaiting the doctor on the map kowloon what you want to do after you intaragate the doctor you want to destroy all the nova six tanks. then there will b a room behind you with a tape player hold X to collect the tape....After you have done this and reach the point where your guys move the fridge too open the weapons volt there will b another tape player to the left. Hold X again when next to the tape player and you will see it go inside and shut. Next your screen will shake and the player will make some funny noises and then when the screen is done shaking the thundergun will appear on the wall......if you run out of ammo dont worry the ammo will come back after everycheck-point