Until the bag gets caught on their tail and they sprint in terror through every area that you've hitherto managed to keep them from destroying, while the bag of death chases behind, literally on their tail. Good times.
Yeh but only if you didn't mean to, like it came that way or you did do it on purpose but for some other reason not cat related specifically. If you set it aside for them because you want them to be happy then they've got no interest in your stupid bag or box.