A customer at Greens Gourmet Grocery marveled at the proprietors quick wit and intelligence. "Tell me, Green, what makes you so smart?" "I wouldnt share my secret with just anyone," Green replies, lowering his voice so the other shoppers wont hear. "But since youre a good and faithful customer, Ill let you in on it. Fish heads. You eat enough of them, youll be positively brilliant." "You sell them here?" the customer asks. "Only $4 apiece," says Green. The customer buys three. A week later, hes back in the store complaining that the fish heads were disgusting and he isnt any smarter. "You didnt eat enough, " says Green. The customer goes home with 20 more fish heads. Two weeks later, hes back and this time hes really angry. "Hey, Green," he says, "Youre selling me fish heads for $4 apiece when I can buy the whole fish for $2. Youre ripping me off!" "You see?" says Green. "Youre smarter already."