We’ve all witnessed it: it’s the end of the semester and the professor’s office is overflowing with nervous students. They’re asking for extra credit, extra assignments, or just a little extra sympathy.
Two economists are walking down the street. One sees a $20 bill lying on the sidewalk and says, “Look at that $20 bill!” The second economist responds, “Nah, that’s not a $20 bill. If it was, someone would have picked it up already.”