Slaughterhouse I

Slaughterhous I is a Minor Easter Egg in the map First Contact. To get it, first kill 800 zombies, You will then hear the Demonic Announcer laughing. Once this is done, make sure you have either the Paddlesaw or the Electronicon, before entering the Danger Room. Without leaving the room, kill 100 zombies. There will then be an explosion of blood, and you will obtain a skull with the roman Numeral I scratched into it's cheek. This Skull can be brought to every level. Zombies will now mover slower, and sometimes be distracted by the blood.