Lemonade Stand

A man sees a lemonade stand run by a small girl. He notices her hand-written sign announcing that 1 glass of lemonade is $1 and that 3 glasses are $5. The man explains to the girl that buying 3 glasses for $5 is more expensive than buying 3 glasses for $1 each. The girl disagrees and says that it costs less to buy 3 glasses for $5. He tries to explain once again, but the girl still says that buying 3 glasses for $5 is cheaper.

Frustrated, the man buys 3 glasses of lemonade for $5, and then buys another 3 glasses of lemonade for $1 each. He shows the girl that he bought the same amount of lemonade for $3 instead of $5 and states that the girl is wrong. The girl then replies, "You are absolutely right. Also, you just bought 6 glasses of my lemonade!"

Moral of the Story: Our need to always be right can often blind us to our own folly.