<Table> <Tr> <Td> "</Td> <Td> By custom, the challenger, usually one of the intermediates, anxious to prove his worth or avenge some wrong, would deliberately seek out his foe with a wood chip or flat stone on his shoulder, placed there either by his own hand or by that of somebody else . </Td> <Td>" </Td> </Tr> </Table> <Tr> <Td> "</Td> <Td> By custom, the challenger, usually one of the intermediates, anxious to prove his worth or avenge some wrong, would deliberately seek out his foe with a wood chip or flat stone on his shoulder, placed there either by his own hand or by that of somebody else . </Td> <Td>" </Td> </Tr> <P> The challenger might further provoke his opponent by issuing a dare for him to knock off the chip . The opponent might then display his bravery and contempt by brushing the cheek of the challenger lightly as he did so . In more formal cases, a second might take the chip and present the chip to his man who would then place it on his own shoulder . The boys would then square off and fistfight like boxers . </P>

Where did a chip on your shoulder come from