This works on an individual non-packaged basis as well

You can learn a lot about a person by the way they respond when you hand them a baggie full of dead rodents.

Hat tip: Chap

Mister Gato still brings us the occasional dead rodent, but I think he means something different by it than Abby.

You can learn a lot about a cat by the way he responds when you put a bag of clean laundry down.