Nate Sr.: You can do anything, you lucky bastard, you're alive! What's a little pain compared to that?
David: It can't be that simple.
Nate Sr.: What if it is?
When Nate Jr. comforts a woman, grieving her aunt who was the only person to ever love her.
Grieving Woman: Why do people have to die?
Nate: To make life important.
Brenda's mother kind of hit the nail on its head when she said this: "Life is so fucking hard, even when it's easy."
Ruth at the self-help seminar: "And fuck you too, for not letting me buy that Snickers!"
"Next time you call somebody a faggot, make sure that faggot is no LAPD cop!"
The last scene, which cuts between Claire driving off to New York City and flash-forwards of all of the deaths of the surviving main characters. It's surprisingly heartwarming while being crushingly heartbreaking in context.