把口張開 She Opened Her Mouth
在肚裡做甚？出來罷。」行者在裡邊叫道：「張開口，等我出來。」那怪真個把口張開。在肚里做甚？出来罢。」行者在里边叫道：「张开口，等我出来。」那怪真个把口张开。
逐句解 Line by line
What is he doing in her belly?
甚 is shén, a clipped 甚麼 with the second character dropped — exactly the way English says whatcha doing. The reading matters: the same character is shèn when it means extremely, as it will be later in this chapter at 窠穴甚多.
Come on out."
罷 is ba, the soft word that turns an order into a suggestion — come out, why don't you. It is the toneless one. The same character carries a full fourth tone, bà, when it means to have done with something, and the chapter will use both.
Pilgrim called from inside, "Open your mouth and let me out."
The comedy of the whole sequence is in the logistics. He is a guest who has to ask his host to open the door — and the host is the person he has been tormenting.
The monster really did open her mouth.
真個 is truly, actually, sure enough — the narrator raising an eyebrow at how obediently she complies. 那 is nà, that one, pointing at her; the same character asks nǎ, which one. It turns up fifty-seven times in this chapter, every one to be judged on its own.
The bargaining position here is absurd and the novel knows it. Pilgrim has total power and no exit; the fiend has an exit and no power. The result is a negotiation conducted through a throat.
The fiend's obedience is the first sign of how thoroughly beaten she is at this stage — and how little that will end up mattering.