Originally Posted by Oberon

Yossarian: Is Orr crazy?
Dr. 'Doc' Daneeka: Of course he is. He has to be crazy to keep flying after all his close calls he's had.
Yossarian: Why can't you ground him?
Dr. 'Doc' Daneeka: I can, but first he has to ask me.
Yossarian: That's all he's gotta do to be grounded?
Dr. 'Doc' Daneeka: That's all.
Yossarian: Then you can ground him?
Dr. 'Doc' Daneeka: No. Then I cannot ground him.
Yossarian: Aah!
Dr. 'Doc' Daneeka: There's a CATCH?
Yossarian: A catch?
Dr. 'Doc' Daneeka: Sure. Catch-22. Anyone who wants to get out of combat isn't really crazy, so I can't ground him.
Yossarian: Ok, let me see if I've got this straight. In order to be grounded, I've got to be crazy. And I must be crazy to keep flying. But if I ask to be grounded, that means I'm not crazy anymore, and I have to keep flying.
Dr. 'Doc' Daneeka: You got it, that's Catch-22.
Yossarian: Whoo... That's some catch, that Catch-22.
Dr. 'Doc' Daneeka: It's the best there is.