Whenever you see a paper bag attempting to dance a hula, there’s probably a cat inside it. And whenever there’s no cardboard box handy, a paper bag will do as well.
Only, please, don’t give a cat a plastic bag to play with, any more than you’d give one to a toddler. Paper bags, perfect. Plastic–no. The cat gets stuck and winds up all upset, and apt to hurt himself trying to escape.