有個真假 Is There a False Head
那們個師父進去，弄做這們個師父出來也。」行者道：「獃子，你且認認是真是假，就哭。」八戒道：「不羞，人頭有個真假的？」那们个师父进去，弄做这们个师父出来也。」行者道：「呆子，你且认认是真是假，就哭。」八戒道：「不羞，人头有个真假的？」
逐句解 Line by line
Such a master went in, and this is the sort of master that comes out again!"
The line works by putting the same word at both ends with different pointing words in front of it — that-sort of master going in, this-sort coming out. It is a shape English can catch with the demonstratives, and the grief is in the symmetry.
Pilgrim said, "Idiot, take a proper look and see whether it is real or false before you start crying."
認認 doubles the verb for identifying something, making it casual and immediate — have a proper look at it. Wukong is still refusing to accept an object as a fact, and it is about to save the whole expedition.
Bajie said, "Shame on you. Is there such a thing as a false human head?"
不羞 is have-you-no-shame, thrown at Wukong for quibbling over his master's remains. The question that follows is a reasonable one and it is exactly wrong, which is the most interesting kind of mistake a character can make.
Bajie's objection is sensible, humane, and completely mistaken. Of course there is no such thing as a false human head — except that there is one lying on the ground in front of him, and he is standing over it accusing his brother of coldness.
The novel keeps arranging its scenes so that the character with the warmer heart reaches the wrong answer and the character with the colder eye reaches the right one. It does not resolve this. It just keeps putting it in front of the reader.