A plastic grocery bag. A thing that many people don't really notice. I reuse all my bags, both paper and plastic and normally get a mix of both from the store. A little known fact is that if you look at the environmental impact of those bags it is actually the plastic that is better for the environment. Of course, that's kind of like arguing which is better for you, lead or mercury. Slowly, they'll both poison you. But I reuse all of my bags. I use them for household chores and as can liners, to carry items around the house, and when I travel. Amazing the uses you can find when you look. Ok, lecture over.