Go to dashboard sign into your friends account download Nuketown zombies, Then start up the game on your friends account when on the game go on the zombies main menu then sign out of your friends account and sign back into your account and then you have done it and you can play on the map. (If you go onto multiplayer or you go back to main menu you will have to do this all over again)
Credit to EliteGlitcherHD
[ Register or Signin to view external links. ]
Recover a "Friends" account that has the Nuketown Zombies map on a Second Controller.(So be signed in to your account on the first controller and your friends account on the other) Go to Dowload history on the second contoller and redownload The Nuketown Zombie map. Then Start up a LOCAL match of Black ops Zombies select the Nuketown Zombies map start it up then end the game. After that you can sign out of your "Friends" account and enjoy Nuketown Zombies for Free Online or Offline.