So, I'm sure you all remember that Zombies is on the multiplayer 'engine' in Black Ops 2. They did this for better matchmaking and being able to do Grief or something of the sort. Well, I started thinking about this and the fact that we have the Perma-Perks, or whatever you want to name them.
What if there are Zombie challenges like there are Multiplayer challenges. But unlike the multiplayer challenges, you can't go into Barracks and look at them. This would explain that there are certain challenges to complete to get the Green Poofs.
Just an idea of mine, and sorry if this has been speculated before. :?