meaning of "put his slippers on his head"

English as a Second Language English Vocabulary, Grammar and Idioms
1

What does this mean?

The Zen master, when asked “What is Zen?” by his students, simply put his slippers on his head and left the room.

2

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It is a zen statement; it means nothing. The zen master did something ridiculous and unexpected to indicate that zen is ridiculous and unexpected when one tries to approach it directly with the question, ‘What is zen?’
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3

Thanks