Sentence:  “Nothing can possibly go wrong.” “Just as you say, sir. But I still have that feeling.” The blood of the Woosters is hot, and I was about to tell him in set terms what I thought of his bally feeling, when I suddenly spotted what it was that was making him <WSD>crab</WSD> the act. 
Meaning of the word marked with <WSD> tags:  To back out of something.