滿口應承 He Agreed Without Hesitating
好大聖，更不說沒有，就滿口應承道：「我怎麼沒牌？但只是剛才領的新牌。拿你的出來我看。」好大圣，更不说没有，就满口应承道：「我怎么没牌？但只是刚才领的新牌。拿你的出来我看。」
逐句解 Line by line
Splendid Great Sage! Far from saying he had none, he agreed to it wholeheartedly. "How should I have no tally?
更不說沒有 is he did not even say he had none — 更 here is gèng, not even, the ordinary intensifier rather than the night-watch reading the same character took two scenes ago. 滿口應承 is to agree with a full mouth, to undertake without hesitation, and 應 is yìng in it — the answering band, not the yīng of ought to.
Only mine is the new tally I was issued a moment ago. Take yours out and let me see it."
剛才領的新牌 is the tally I was issued just now — a claim that explains why it might look different and why nobody has seen it. And then the reversal: 拿你的出來我看, the man being checked asking to check the checker. Seven characters, and the interrogation has changed direction.
Asked for identification he does not have, Pilgrim agrees enthusiastically that he has one, adds that it is a new issue, and asks to see the other man's.
Every move is doing work. The enthusiasm removes suspicion, the newness explains any difference, and the request for the other tally is the only way to find out what a tally looks like.
It is a confidence trick of the purest kind, and its whole method is to make the mark produce the evidence himself.