認得豬嘴 You Surely Know the Snout
八戒低著頭，拱著嘴道：「不羞，就拿出這副嘴臉來了。我和你兄弟也做了幾年，又推認不得，說是甚麼夷人。」行者笑道：「擡起頭來我看。」那獃子把嘴往上一伸道：「你看麼，你認不得我，好道認得嘴耶。」行者忍不住笑道：「豬八戒。」他聽見一聲叫，就一轂轆跳將起來道：「正是，正是，我是豬八戒。」他又思量道：「認得就好說話了。」八戒低着头，拱着嘴道：「不羞，就拿出这副嘴脸来了。我和你兄弟也做了几年，又推认不得，说是甚么夷人。」行者笑道：「抬起头来我看。」那呆子把嘴往上一伸道：「你看么，你认不得我，好道认得嘴耶。」行者忍不住笑道：「猪八戒。」他听见一声叫，就一毂辘跳将起来道：「正是，正是，我是猪八戒。」他又思量道：「认得就好说话了。」
逐句解 Line by line
Bajie, head lowered and snout thrust out, said: "Shameless — putting on this face at me! You and I have been brothers these several years, and now you make out not to know me, calling me some outlander."
In 低著頭 and 拱著嘴 the 著 is zhe; 認不得, cannot recognise, takes 得 as de; 甚麼 takes 甚 as shén. 推認不得 is to pretend not to know somebody — and the injured tone is perfect, because Bajie is genuinely offended by a joke he can see through.
The Pilgrim laughed: "Lift up your head and let me look."
Having had his sport, Wukong consents to look. The recognition is one line away.
The blockhead thrust his snout upward: "There, look! If you don't know me, surely you know the snout."
The whole scene resolves on a nose. 那 is pointing nà; both instances of 認得 and 認不得 take 得 as de. If you do not know me, you know the snout: it is unanswerable, and there is not another face like it in the world.
The Pilgrim could not help laughing: "Zhu Bajie!"
The laugh gives him away. Saying the name ends the game.
Hearing his name called, he rolled straight up onto his feet: "The very one, the very one — I am Zhu Bajie!"
一轂轆 is with a roll, tumbling over — the sound and shape of a barrel going end over end; in 跳將起來 the 將 carrying the motion is jiāng.
And he thought: "Now that he knows me, it'll be easier to talk."
認得 takes 得 as de; 思量, to ponder, takes 量 as liáng. And the calculation begins. He has an errand and a lie to tell, and the first hurdle is behind him.
The scene resolves on a purely physical joke — Bajie's snout as an identity card that no pretence can override. His indignant "if you don't know me, surely you know the snout" is the perfect retort of a buffoon whose entire character is written on his face, and Wukong's helpless laugh gives away the affection under the teasing.
The closing calculation turns the scene from comedy toward purpose. The reunion done, the reluctant errand can start in earnest — and the reader is reminded that Bajie is carrying the horse's stratagem, which he must now work on a Wukong who has no idea why he has come.