Go to the multiplayer level Zanzibar. When it starts, run over to the large base and go up to where the rocket launcher is. From there turn around and to your right and left there will be 2 grey doors, that kind of look like garage doors. Jump up onto the ledge in front of them and you can see Ling Ling's head painted on them. Its fairly big, so you should step back a little bit to see it!!! You dont have to do the code on your xbox to see it, its always there.