This is probably my favourite Zen story:

Whenever anyone asked him about Zen, the great master Gutei would quietly raise one finger into the air. A boy in the village began to imitate this behavior. Whenever he heard people talking about Gutei's teachings, he would interrupt the discussion and raise his finger. Gutei heard about the boy's mischief. When he saw him in the street, he seized him and cut off his finger. The boy cried and began to run off, but Gutei called out to him. When the boy turned to look, Gutei raised his finger into the air. At that moment the boy became enlightened.