What does it mean to knock on the deck and let the big fish get out of the way?
This is the lyrics of Spongebob theme song in Chinese translation. The original English text was thrown on the deck, flapping like a fish. I fell on the deck and rolled like a fish. This sentence itself has no clear meaning, mainly a cheerful atmosphere. The first sentence of the theme song is if childish nonsense is what you want, which literally translates as "if nonsense is your deep-sea dish", so the next sentence has no specific meaning.