I actually did something like this a couple of years ago.
I was near HWY 100 walking home and a car pulled up to turn out of a gas station. I saw them crinkle up a wrapper and toss it out their window. Luckily, they didn't have time to pull out until after I reached them. So I casually leaned over, picked up the garbage, and sarcastically said, "Hey, I think you dropped this" while I tossed it back into their open window.
It felt so good.