Check out this story (
AP/Yahoo link). In a nutshell, Jeffrey Skilling was running around New York, allegedly pulling on people's clothes, and shouting "You're an FBI agent and you're following me". On one hand, it may be a masterful exercise in pre-emptively declaring himself to be incompetent to stand trial. On the other hand, maybe the pressure is getting to him a bit.
Some might argue that Lea Fastow's behavior could also be considered
somewhat insane. She wanted a guaranteed 10 month sentence, 5 in prison, 5 confined to home arrest. Her plea agreement was done in conjunction with her husband (Andrew Fastow) pleaing and agreeing to help make a case against the higher brass. The judge wanted the leeway to go as high as 16 months of prison for Lea (standard federal guidelines for the criminal charge in question), not accepting the negotiated 10 months. By forcing things to a trial, Lea now faces some six charges rather with a combined worst-case sentence of 37 years in prison. I ain't a lawyer, but it sounds like she should have sucked it up and taken the plea bargain.