Bob Ewell's got a kitchen knife in his craw.

This phase is based on the old Australian idiom; a stick in ones craw. If something ‘sticks in ones craw’ it mean that something is unacceptable and has therefore annoyed you. In this context, Harper Lee has changed to idiom to represent two things. The first, the use of the original idiom representing that Bob Ewell has been annoyed at the fact that his reputation is now ruined by Atticus, and of course, that he is now dead. She then changes the idiom to say ‘kitchen knife’ instead of stick, as Bob Ewell was recently stabbed with a kitchen knife.