颼者走也 Whoosh Means Run Off
大聖在他頭上，也忍不住道一聲「我的兒啊，颼者走也。」眾怪聽見道：「走了，走了。」即傳令：「關門，關門。」大圣在他头上，也忍不住道一声「我的儿啊，飕者走也。」众怪听见道：「走了，走了。」即传令：「关门，关门。」
逐句解 Line by line
The Great Sage, up on his head, could not help saying, "My boy — sōu means run off!"
He answers the formula with the same formula. 颼 is the whirring noise the drill made four passages back, and he has turned it into a word and glossed it in the demon's own scholarly register. 我的兒, my boy, is Wukong's standing insult — he calls almost every monster in the book his son.
The demons heard it and said, "He's gone! He's gone!"
They repeat it, as this cave repeats everything.
And at once the order went out: "Shut the doors! Shut the doors!"
The same order, in the same doubled shape, as the one the old fiend gave at the start of all this. The cave has one response to everything and it has now used it twice on a monkey who is inside with them.
This is the chapter's best exchange and it works because both parties are showing off. The demon glosses 空; Wukong, sitting on his head, glosses 颼 — turning the sound of his own escape into a lexical entry. It is a joke about pedantry made by two creatures who cannot stop performing.
忍不住 twice in two sentences, once for each of them, and this is its fourth appearance in the chapter. It gave away Wukong's disguise, it produced his tears in the bottle, and here it produces a wisecrack from inside the enemy's hall when silence would serve better. The book is not tracking a flaw; it is tracking a temperament.