On the sidewalk? I pick it up. If it's someplace like at work or somewhere I actually know people, I'll try to find who's it is (won't ask them if they dropped a $100 bill, but asked them if they dropped some money and how much).
Unless I actually saw the person on the sidewalk or random public dropping the bill, I don't feel bad about keeping it because a good 90% of people would flat out lie if you asked them about it.








