Silvia Johnson, who became known as the "Cool mom" for partying with her children and their teenage friends, pleaded guilty this morning to a charge of violating bond conditions. Johnson, 41, is serving a 30-year sentence for plying high school boys with liquor, drugs and sex. She was charged with violating bond conditions and a protective order that barred her from contact with some of her children, while she was free awaiting sentencing. Johnson was arrested on the new charges after a Sept. 25 car crash in which a 14-year-old girl was driving. Johnson and a carload of teens, including...