Pilgrim said: "How could you hope to hide it from me?

瞞得過, mán de guò, is the can-you-manage-it form: not merely to try to hide a thing but to get it past someone successfully.

When I tug my left ear upward, I can make out the speech of the beings in the Thirty-Three Heavens; when I tug my right ear downward, I can make out the reckonings of the Ten Kings of the Underworld and their judges.

Here is the boast everybody remembers. 三十三天, sān shí sān tiān, is Trāyastriṃśa, the heaven of thirty-three gods on the summit of Mount Sumeru; 十代閻王, shí dài Yán wáng, are the Ten Kings of the underworld, and a 判官, pàn guān, is the infernal magistrate who keeps their ledgers. Wukong can eavesdrop on the top and the bottom of the universe by tugging an ear — and here he is using it to catch a pig grumbling on a road.

Just now, as you walked along cursing me, how should I not have heard?"

豈不, qǐ bù, is the rhetorical "how could I not."

Bajie said: "Brother, I knew that, sly and furtive as you are, you'd surely change into some little thing or other and come tagging behind me to listen."

Bajie's counter-accusation is affectionate abuse. 賊頭鼠腦, zéi tóu shǔ nǎo, is "a thief's head and a rat's brains" — shifty, sneaking, forever round a corner. 東西兒, dōng xi'r, is colloquial "some little thing or other," with the 兒 suffix curling the end of the word; 跟著, gēn zhe, has the "-ing" sense, tagging along behind.

Pilgrim called out: "You little ones — fetch the big cudgels! First give him twenty across the shins to greet him, then twenty flowering welts across his back, and after that let me take my iron rod and give him a send-off."

The threatened punishment is delivered in courthouse slang. 見面孤拐, jiàn miàn gū guǎi, is a crack across the shin-bone by way of hello; 背花, bèi huā, "back-flowers," are the welts a flogging raises — the blossom is the bruise. And 送行, sòng xíng, "to see someone off," is being applied to a beating that would send him off for good.

Bajie, flustered, knocked his head on the ground and said: "Brother, by all means think of our master's face — spare me, I beg you."

慌得, huāng de, "so flustered that"; 千萬, qiān wàn, literally "a thousand times ten thousand," which is how Chinese says "whatever you do, please."

Pilgrim said: "I fancy that master of ours is a fine, righteous soul indeed."

好仁義兒, hǎo rén yì'r, "quite the righteous soul" — delivered with a sideways look. 哩, li, is a colloquial tag hung on the end of the sentence, about the weight of a shrug.

Bajie said again: "Brother, if not for our master's sake, then for the sake of the Bodhisattva of the sea — spare me, I beg you."

海上菩薩, hǎi shàng pú sà, is Guanyin, whose island of Potalaka lies in the Southern Sea. Bajie has climbed from the master's name to the Bodhisattva's — and the next passage shows that the second rung holds.