The teacher asked to meet with Johnny's parents. 'I think your son cheated on a school test,' the teacher told the parents. 'What do you mean?' the parents asked. 'Well,' said the teacher, 'I compared your son's completed test with the boy sitting beside him and I found that both had the first three answers right and the next two wrong.' 'That doesn't prove anything,' said the parents.
'That's what I thought,' said the teacher, 'until I came to the sixth question.' 'What about the sixth question?' asked Johnny's parents. 'Well,' answered the teacher, 'to the sixth question, the boy sitting beside your son had answered, 'I don't know'; and your son answered, 'neither do I.''