Jean Louise leaves her uncle's house thinking he's "mad as a hatter" (15.1) and too old to be relevant.
Speaking of no longer relevant, Jean Louise has a really long flashback about going to her first dance with Henry.
Here's how it goes down (in the present tense, just to keep it fresh):
She's insecure about her figure, and she puts falsies in her bosom (i.e., stuffs her bra) to look more, uh, buxom.
Uncle Jack teaches her to dance, and Atticus says she "look[s] like a picture" (15.73). Funny: Atticus used the same line as an insult to Miss Dubose in To Kill a Mockingbird.
He tells her, "I hope you have the time of your life." (15.58). Time of your life? Is he endorsing Dirty Dancing?
The dance is like Happy Days meets She's All That because Scout is the prettiest one there. Everyone can't stop looking at her.
She dances with everyone and only misses one step.
But then her fake boobs slide out of place. Henry points out that her falsies are hangin' low, that they're wobbling to and fro, and she runs from the party embarrassed—like Cinderella losing her implants instead of a glass slipper.
Henry takes the fake boobs and flings them into the darkness. He thinks Scout looks better without them.
No one seems to notice, and she has a good time.
However, the next day at school, the principal is furious: he found the falsies dangling from a billboard, and he considers it a crude joke.
Scout and Henry argue over who should confess. Scout and Jem are afraid that if Henry confesses, the principal will expel him.
Henry skips study hall, and when he returns, he tells Scout to write a note: "Dear Mr. Tuffett. They look like mine" (15.190).
Scout writes the note and gets called into the principal's office.
He shows her dozens of other notes like hers. Henry had convinced almost every girl in school to confess.
Scout gets off with only an hour detention.
Henry reveals that he went to consult Atticus, and it was Atticus's idea...in a way. He suggested there is "safety in numbers" (15.202).
Back to the present, Jean Louise crushes a paper cup, mad that she doesn't belong to her family anymore.