While you are completing the very first mission in the game, called Ghost Hideout, you are killed and will need to make use of a defibrillator to bring yourself back to the land of the living (this is all part of a tutorial). After this happens you move to the next part of the mission of take care of some enemies there.

In thispart there is a TV. What you need to do is stand on the right hand side of it which will also place you in a corner. When you are positioned there press the interact button and you will open a secret door to a Wolfenstein themed room. Inside is a Wolf Goblet which can be sold for $150.

Note you can't get back into the room after finishing the mission! There are other rooms throughout the game like this one with Quake and Doom themes too.