After a trial had been going on for three days, John Smith—the defendant—stood up and approached the judge's bench.
"Your Honor, I would like to change my plea from innocent to guilty of the charges."
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.
Smith looked up wide-eyed and said, "Well, when the trial started, I thought I was innocent, but that was before I heard all the evidence against me." (from Cybersalt Digest)