I know the meaning of 'lockjaw', which is a kind of disease but I don't think this word from the sentence below doesn't literally means that disease but other thing.
This is some part from a novel 'Baker's Blue-jay yarn' by Mark Twain.
[You may say a cat uses good grammar. Well, a cat does - but you let a cat get excited once; you let a cat get to pulling fur with another cat on a shed, nights, and you'll hear grammar that will give you the lockjaw.]