少半盞 Something Less Than Half
你看他往前撲了一撲，往後蹲了一蹲，咬得那滿口牙齕支支的響喨，僅努出幾點兒，將身立起。八戒道：「這個亡人，就是金汁子，再撒些兒也罷。」那行者見有少半盞，道：「夠了，夠了。拿去罷。」沙僧方才歡喜。你看他往前扑了一扑，往后蹲了一蹲，咬得那满口牙龁支支的响喨，仅努出几点儿，将身立起。八戒道：「这个亡人，就是金汁子，再撒些儿也罢。」那行者见有少半盏，道：「够了，够了。拿去罢。」沙僧方才欢喜。
逐句解 Line by line
Watch him: he lunged forward once, squatted back once, ground the whole mouthful of his teeth till they rasped and rang, strained out a bare few drops, and stood up again.
你看他 — watch him — and then five verbs of effort against one adverb of result. 齕支支 is the sound of grinding teeth. 咬得 takes the light de, 兒 the light suffix, and both 一 shift tone in the ordinary way.
Eight Rules said, "You wretched creature — even if it were liquid gold, you might let out a little more."
金汁 — liquid gold — really is the name of a medicinal preparation, so the insult and the pharmacopoeia turn out to be the same word. 也罷 is a set phrase and keeps bà, against the light ba the same character takes a line further on.
Pilgrim, seeing there was something under half a cupful, said, "Enough, enough. Take it away."
罷 is the light ba here, the little word that softens an order into a suggestion — not the bà of 也罷 in the line before.
Only then was Sha the monk content.
The last word goes to the man who objected to the ingredient in the first place, and he is content. Nobody won the argument.
Five verbs for the effort and one adverb for the result. He lunges, squats, grinds his teeth until they rasp and ring, strains out a bare few drops, and stands up again — and the narrator opens with "watch him", inviting you to enjoy it.
Eight Rules is not satisfied, and complains in the form of an insult with a joke buried in it. Liquid gold really is the name of a medicinal preparation, so the abuse and the pharmacopoeia turn out to be the same word.
Pilgrim calls a halt at something under half a cupful, and the last line goes to Sha the monk — who objected to this ingredient in the first place and is now the one who is satisfied. That is the narrator's way of saying the argument is over and nobody won it.