好大面皮 A Very Large Face
葛仙翁道：「俗語云：『蒼蠅包網兒──好大面皮。』」許旌陽道：「不要亂談，且只帶他進去。」葛仙翁道：「俗语云：『苍蝇包网儿──好大面皮。』」许旌阳道：「不要乱谈，且只带他进去。」
逐句解 Line by line
The Immortal Ge said, "As the common saying goes: a fly wrapped in a net — what a very large face."
This is a two-part folk saying of a kind Chinese has a name for, in which the first half is a picture and the second half is the point. A fly caught in netting has a huge mesh stretched across its tiny face, and 面皮, face-skin, is also the ordinary word for nerve or cheek — so the punchline means what a lot of nerve you have. The pun does not survive translation, and it is the whole joke.
The Immortal Xu said, "Stop talking nonsense. Just take him in."
許旌陽 is Xu Xun, a fourth-century figure remembered for subduing a flood-dragon and later venerated as an immortal — another real person given an office in this heaven. His line is the flat one that ends the banter.
One of the celestial officers makes a joke at Pilgrim's expense, and it is a genuinely good one. A fly wrapped in netting has an enormous face — and having a large face, in Chinese, means having some nerve.
It is the kind of wordplay that dies on the operating table in translation, but the social move survives: Pilgrim has just said let us see what my standing is worth, and a colleague has replied, in effect, the cheek of you. They are teasing him. Nobody up here is afraid of him any more, and nobody is hostile either. He has become someone they rib in the corridor.
Then the other one tells him to stop and take the monkey through. Even the banter runs on protocol.