Overheard at the Grumpy house computer desk

Frank: "Don't click on that button."

Craig: "Why not?"

Frank: "You know."

Craig: "I don't know."

Frank: "It will erase your file."

Craig: "How do you know?"

Frank: "I don't know."

Craig: "You don't know?"

Frank: "I know that you don't know."

Craig: "You don't know what I know because you don't know!"

Frank: "You don't know that!"

Craig: "I know!"