My favourtie Simpsons quote is not really a quote, but a scene, one of the best scenes in my opinion, and it's is when Homer is paranoid he's going to die:
Dr. Hibbert: Now, a little death anxiety is normal. You can expect to go through five stages. The first is denial.
Homer: No way! Because I'm not going to die!
Dr. Hibbert: The second is anger.
Homer: Why you little...!
Dr. Hibbert: After that comes fear.
Homer: What's after fear? What's after fear?
Dr. Hibbert: Bargaining.
Homer: Doc, you gotta get me out of this! I'll make it worth your while!
Dr. Hibbert: And finally, acceptance.
Homer: Well, we all gotta go sometime.
Dr. Hibbert: Mr. Simpson, your progress astounds me!