If Casey hadn't killed Caylee, when she first got to the visiting booth, she may have expected to hear news of Caylee, perhaps she would think, "Oh, they've found her, she's okay and they're here to let me know". Any normal person would have eagerly asked for information about the child. But instead of inquiring if they know where Caylee is, or if she's home, she grabs the phone all chipper and says, "Good morning". Is that really what an innocent, loving mother would do?
G&C should have gotten a clue right there. Maybe they did.
Cindy was asking questions, Casey wasn't giving answers, Cindy asked more and more questions. Casey went wild. Cindy calmed down and stopped asking the questions.
Casey was frustrated because they were asking what she knew about Caylee's whereabouts and her disappearance. Casey had already told them everything she planned to tell them. Why were they still asking? They always accepted her lies before. Now they are asking beyond the realm of Casey's planned script. She had no more answers, she wanted out of jail, she was miserable, and they only wanted to talk about Caylee. How dare they when Casey's entire life was ripped away? Talking about a dead kid wasn't helping Casey get out of jail. It was all about Casey and there was Cindy asking for more clues, more information about finding that dead Caylee. How dare she?
And that's why the prisoner went ballistic. Lake County may have meaning but I think Casey's predicament and her parents callous disregard for it were what sent her into a tizzy. They were worried about Caylee who was dead while Casey was living a life of hell in jail!!!