This is a video you have to see: Former NFL star CHAD JOHNSON - a.k.a. Chad Ochocinco . . . got arrested IN COURT because he slapped his attorney's backside. 

Chad was in a Florida courtroom finalizing a plea agreement for a probation violation. Sources say it was a pretty sweet deal for him. But he messed it up royally. The judge asked him if he was happy with his attorney, and he said yes. Then she agreed with him and started praising his lawyer, so Chad thought it would be cool to give the guy a congratulatory pat on the buttocks.

Everyone in the courtroom laughed, which made things even worse. The judge FLIPPED. She said, quote, "I don't know that you're taking this whole thing seriously . . . is there something funny about what's going on here today?" Then she REFUSED to accept the deal. Instead, she ordered Chad to be CUFFED and taken to jail for 30 days. The whole thing lasted less than 3 minutes. Watch here how it unfolded and the Judges reaction.