"You bet she ain't," he exclaimed.

"She can't.
The whole yarn's a lie.

Don't pay no attention to it, Pop." Shadrach turned sharply in his direction.

"I'M payin' attention to it," he snapped, "and that's enough.

So you ain't goin' to tell, Mary-'Gusta, eh?
Remember now, if you do tell it'll prove your story's true and David'll come out on top.