Holden sneaks into his family's apartment. He finds Phoebe in D.B.'s room, where she likes to sleep when D.B. is away. Holden notices how children look much more peaceful than adults do when asleep.
A familiar contrast between children and adults, with children once again coming out on top in Holden's estimation.
While Phoebe sleeps, Holden looks through her school notebooks. Her scribbling and drawings delight him and he likes that she's signed her name: "Phoebe Weatherfield Caulfield." Her real middle name is Josephine.
Only children and childish things delight Holden. He likes things that are random and don't follow the rules.
Holden wakes Phoebe up. She's overjoyed to see him and floods him with news, from her role as Benedict Arnold in the school play, to a movie she saw, to the fact that their parents are out at a social event and won't return until later that night.
In some respects, Holden is right about children versus adults. Unlike adults, Phoebe immediately accepts Holden and is open with him, not phony.
Phoebe then realizes Holden is home two days too early. Holden admits he got expelled. Phoebe keeps repeating that their father is going to "kill" him. Holden tries to calm her, but she covers her head with a pillow.
Holden tries to hide from the adult world. Phoebe tries to hide from Holden. She can sense he's in trouble.
Holden tells her not to worry: he's going away to a ranch in Colorado. She keeps the pillow over her head. Holden calls Phoebe a "true madman."
Holden makes another unintended ironic statement about insanity. Clearly he's the madman.