Two economists were walking down the road and spot a $20 bill on the ground. "Is that a $20 bill?" one asked. "Couldn't be, someone would have picked it up by

Two economists were walking down the road and spot a $20 bill on the ground. "Is that a $20 bill?" one asked. "Couldn't be, someone would have picked it up by now" replied the other, and they went on their way.