Here is another cool Easter egg you can find on the Blood of the Dead map. But before you can find it, you must get either a Spoon or a Gold Spork. Both are melee weapons that can be found on the Blood of the Dead map.
Once you have obtained one of the weapons, head toward the Warden's building. As you enter the building, go upstairs and turn toward the wall and scratch it using either a Spoon or a Spork.
Lastly, go outside and wait for the Brutus zombie to appear. Let him follow you back into the Warden's house to the spot where you've scratched the wall upstairs and let him slam you.
This will create an explosion that will reveal the secret Warden's room with lots of cool items inside.