My mother in law used to use Cool Whip containers for leftovers. When we'd visit, she'd send us home with food packed in them. Usually stuff like mashed potatoes, but often good stuff too. And when we'd visit her in a few weeks/month, she'd ask where her containers were. This was a generation that saved EVERYTHING. The idea of throwing something out was disrespectful. Waste was the worst of many mortal sins. All because of the Great Depression.