Hank: Most of the time I just keep to myself. I think like what it would be like to be... someone else.
Lee: This is my sister we're talking about. We're not gonna let her die just so you can have one of your moods.
Bessie: Goofy carried me to Mickey's house?
Ruth: How could one sister be so good and the other so bad?
Bessie: Dad's dying. He's been doing it for about twenty years so I don't miss anything.
Lee: We call it the loony bin, or the nut house, to show that we've got a sense of humor about it.
Answer: Lee is being an overbearing mother with strict rules and Hank is a little mentally unstable (most likely because of Lee's parenting). Hank is just resisting his mother and probably even felt embarrassed and angry. It's a scene meant to show the strained relationship Lee and Hank have.
Bishop73