一片子臊泥 A Lump Of Stinking Mud
那三藏聽見行者現了相，在空中降妖，嚇得魂飛魄散。幸有八戒、沙僧護持，他又臉上戴著一片子臊泥。那三藏听见行者现了相，在空中降妖，吓得魂飞魄散。幸有八戒、沙僧护持，他又脸上戴着一片子臊泥。
逐句解 Line by line
As for Tripitaka, when he heard that Pilgrim had shown his true form and was subduing a fiend up in the sky, he was frightened out of his wits.
魂飛魄散 — souls flown, spirits scattered — is the same two-soul idea the battle poem used a few passages back, and it is still the ordinary Chinese for being scared witless. Note what actually frightens him: not the demon, but the news that his disciple has dropped the disguise. Tripitaka spends most of this novel terrified of being noticed. 降 is xiáng, subduing — not the jiàng of descending.
Luckily Bajie and Sha Monk were there to look after him, and besides, he still had a lump of stinking mud plastered over his face.
The mud is a leftover from the previous chapter, where Wukong smeared it on so that his master could pass as somebody else while the impersonation was running. 臊 is a specific kind of foul — the rank smell of urine or of an unwashed animal — so this is not decorative dirt. 一片子 is a colloquial measure phrase, closer to "a patch of" than "a piece of." 戴著 takes zhe: the mud is still on him.
The novel cuts back to the people who have been left out of the action, and finds them exactly where it dropped them: frightened, unwashed and uninformed. This is one of the book's best running jokes about its own hero — Wukong resolves a national crisis and forgets to tell anyone.
The detail of the mud is going to run for several passages. It is the kind of small physical indignity the novel loves to visit on Tripitaka, who is the only member of the party who cares how he looks.