A better place to camp is teleporter A and have 2 people cover the windows, then the other two people cover the front door. Everybody gets bouncing betties, and plants them randomly throughout the room far away enough from each other. The people at the windows try to get crawlie zombies at their windows, then everybody goes out to do whatever they want money wise, and switch off guarding duties. Me and my friends (total of 4) got to level 25 dong that, and we hardly ever play call of duty