Two economists are walking down the street. One sees a $100 bill on the ground and says, "Hey, isn't that a $100 bill?" The other laughs-- "Of course not. If it

Two economists are walking down the street. One sees a $100 bill on the ground and says, "Hey, isn't that a $100 bill?" The other laughs-- "Of course not. If it was, someone else would have taken it by now." While I agree with you in this specific case, this joke always pops into my head whenever "efficient markets" are brought up.