化身促織 Changed into a Cricket
好大聖，笑唏唏的，將鐵棒藏了。跳下高峰，又至洞口，搖身一變，變作一個促織兒。真個：好大圣，笑唏唏的，将铁棒藏了。跳下高峰，又至洞口，摇身一变，变作一个促织儿。真个：
逐句解 Line by line
The fine Great Sage, chuckling to himself, put the iron rod away.
笑唏唏的 is "with a snickering laugh." 將鐵棒藏了: 將 is jiāng, the word that puts an object in front of its verb; 藏 is cáng, to stow or hide away, not the zàng of 三藏, Tripitaka's name; 了 is le.
He sprang down from the high peak, came again to the cave mouth, shook himself, and changed into a cricket.
Of all the shapes available to him, he picks a cricket. 促織兒 is the cricket (standard name 蟋蟀), with 兒 as the ending er. The name literally means "urge-the-weaving" — the insect whose chirring in autumn was said to hurry the women along at their looms before the cold arrived. It is the sound of a deadline.
Truly:
The tag announcing the verse gets its own segment and is not itself verse. What follows is a 詞, a song-lyric, in the 西江月 measure — two stanzas of six, six, seven and six syllables — rather than the seven-syllable couplets used for the fighting.
Hard of mouth, long of whisker, black of hide; / bright of eye, with claws and feet splayed wide.
First line of the lyric, six syllables. 鬚長: 長 is cháng. 丫叉 means forked or splayed. Before it is anything else, this is accurate insect description: hard mouthparts, long antennae, dark body, splayed legs.
In clear wind and bright moon it calls from the foot of the wall;
The seven-syllable third line of the stanza. 牆涯 is the foot of a wall, the cricket's classic station in Chinese verse.
in the stillness of night it is like a person talking.
如同人話 — the old conceit that a cricket's cry sounds like someone talking. It also quietly sets up the plot, because this particular cricket is about to do a great deal of listening.
Weeping dew, a scene of chill desolation; / a voice broken off and taken up again, worth the praising.
The second stanza opens. 泣露, "weeping dew", is a standing figure for autumn insects; 斷續 catches the way the chirring stops and starts.
At the traveller's window his wandering thoughts dread to hear it;
客窗旅思 — the traveller at his window — is the classic posture of homesickness in Tang and Song poetry; 旅思 is a wanderer's brooding.
and it is precisely there, on the empty steps, beneath the bed.
偏在 means "is right there, of all places." 空階床下 closes the lyric exactly where the insect actually is: on the empty steps, under the bed. Which is also where the burglar intends to be.
This is the smallest transformation Wukong performs in the whole arc, and the narrator marks it with a full lyric — a 詞 in the 西江月 measure, two stanzas of six, six, seven and six, rather than the seven-syllable couplets used for fighting. The form matters. 西江月 is a song-measure with a long pedigree in melancholy, and the poem it carries here is a proper autumn-insect piece: weeping dew, a voice that breaks off and starts again, the traveller at his window who dreads to hear the sound. Nothing whatever in it is about burglary.
That is the joke, and it is a fine one. The cricket, 促織, "urge the weaving", is the insect of homesickness — the creature whose chirring, from the Book of Odes onward, tells a traveller how far he is from home and how late the year has got. The narrator hands it the full weight of that tradition, ends on 怕聞他, "they dread to hear it," and then sends it in under the door to case a demon's bedroom. The reader is invited to notice that the fiends inside genuinely ought to dread hearing this particular cricket — and that Wukong, who is a very long way from home himself, is about to spend the night at the foot of somebody else's bed.