I have a cat who has fascinations with boxes. If you get anything in the mail and you open the box....I usually shove the box into the hallway for disposal later. In ninety-nine percent of cases....I will find the box occupied by "Mister Fluffy".
It's an obsession of sorts with him. He'll sit in the box for an hour or two....maybe longer. I suspect he's thinking it's a long-term box, or maybe it's just something new to investigate.
It's hard to tell Mister Fluffy that the game is over....the box has to go. He'll just sit there and let you know it's part of his empire now. I suspect he'd be in hog-heaven if he could be relocated to a box-factory somewhere.