How does Scout shock Uncle Jack? What warning does Uncle Jack give Scout about her swearing?

Scout has been trying out swear words on the theory that Atticus won't make her go to school if he finds out she learned them there, but after dinner Uncle Jack tells her not to use them in his presence unless she's in an extremely provoking situation.

When Uncle Jack comes upstairs to have a talk with her about her language. Scout points out that he doesn't understand children very well, since he never heard her side of the story. Uncle Jack asks her for her side and Scout tells him what Francis said about Atticus.