At the beginning of each opponent's upkeep, that player moves a permanent they control to touch Cramped Bunker and no other permanents. If the player can't, destroy each permanent they control that isn't touching Cramped Bunker, then sacrifice it.
1/19/2018 You can pick up cards touching Cramped Bunker to tap them if you need to, but then they must end up still in contact with Cramped Bunker and not in contact with any other permanents.
1/19/2018 If a token is put in the Cramped Bunker, the object being used to represent the token is what must get in the bunker. You’re not allowed to change what that object is once Cramped Bunker appears. For example, if you’re using a Zombie token card to represent an Angel token (weird, but sure), you can’t suddenly decide you’d rather use a penny. If you create a new Angel token, you can use a penny.