Two Keynesian economists, John Maynard Keynes and Paul Krugman, were walking down the street one day when they passed two large piles of dog shit.
Keynes said to Krugman, "I'll pay you $20,000 to eat one of those piles of shit." Krugman agrees and chooses one of the piles and eats it. Keynes pays him his $20,000.
Then Krugman, feeling richer, says, "I'll pay you $20,000 to eat the other pile of shit." Keynes, feeling bad about the money he lost says okay, and eats the shit. Krugman pays him the $20,000.
They resume walking down the street.
After a while, Krugman says, "You know, I don't feel very good. We both have the same amount of money as when we started. The only difference is we've both eaten shit."
Keynes says: "Ah, but you're ignoring the fact that we've increased the GDP by $40,000."
