Hmmmm interesting I haven't seen that one yet. No clue what that or the box perma perk does exactly. Gonna take some trial and error.
Not 100% on the mystery box persistent upgrade, but everyone is saying it gives you better weapons. To activate just keep using the box until it moves and the next time you use it, supposedely you get the green flash and the teddy bear appears on top of the box. Heard that if you use it too many times or if it gets past round 10 the perk ends, but not 100% on all that info. Maybe more to it.
Actually to activate it (for me at least) is hit it like four to five times and you'll get the green flash.