Guilty

After a trial had been going on for three days, Clark, the man accused of committing the crimes, stood up and approached the judge's bench.
Your Honor, I would like to change my plea from innocent to guilty, he said.
The judge angrily banged his fist on the desk. "If you're guilty, why didn't you say so in the first place and save this court a lot of time and inconvenience? he demanded.
 

Clark looked up wide-eyed and stated: Well, when the trial started I thought I was innocent, but that was before I heard all the evidence against me.