我們是 One Word Wakes the Sleeper
當殿官同眾至館中，即問看館的道：「那個是大唐取經僧的高徒？我主有旨，請吃齋也。」八戒正坐打盹，聽見一個「齋」字，忍不住跳起身來答道：「我們是，我們是。」当殿官同众至馆中，即问看馆的道：「那个是大唐取经僧的高徒？我主有旨，请吃斋也。」八戒正坐打盹，听见一个「斋」字，忍不住跳起身来答道：「我们是，我们是。」
逐句解 Line by line
The officer of the hall went with the others to the guest house and asked the keeper, "Which of them are the eminent disciples of the scripture-seeking monk of the Great Tang?
看 is kān here, to mind or keep — the man who looks after the building, not someone looking at something. 那 is nǎ, which. And 高徒, lofty disciple, is a courtesy for another man's pupil, the way one might say your distinguished student. Applied to what is actually sitting in that room, it is about to look very odd indeed.
My lord has issued an order inviting them to a meal."
有旨, there is a command, is the formal way of reporting a ruler's instruction, and it is another small confirmation of the prince's rank: his word is an order, not a request.
Bajie was sitting there dozing. Hearing the single word "meal" he could not hold himself back, sprang to his feet and answered, "That is us, that is us."
The best sight gag in the chapter, and the text sets it up with total precision: he is asleep, and one character wakes him. 打盹 is to nod off, still the ordinary word for it. 齋 is the meal itself, and the novel puts it in quotation marks so you can see it working as a single sound reaching a sleeping ear. His answer doubles, just as the officers' answer doubled a moment ago, so the two halves of the scene rhyme.
Everything about this is engineered for the stage. Three monks sit in a room, one of them asleep. An official comes in and asks a polite question, and the word for dinner detonates.
The joke depends on Bajie being characterised so consistently over so many chapters that the reader knows exactly which word will wake him. It would not work in the first ten chapters of the novel; it works here because the audience has been trained.
And notice the answer he gives. Not a greeting, not a name, not an explanation of who they are. Just yes, that is us, twice, delivered by a man who is on his feet before he is properly awake.