My friend has no respect for her parents......how do i tell her...?

My friend is a very outspoken person and believe that she has a right to her opinion, and can tell anyone to shutup and listen to HER side of the story. She is 15 years old, lacks a sign of respct for authorites. In school, she didn't like something that the teacher did so she gave her attitude, swore at her, and yelled at her. I was so appalled, i tried to straighten her out a bit but she only started yelling at me and said "OH MY GOD, I HAVE A RIGHT TO MY OPINION, AND I DONT GIVE A ***** WHAT YOU SAY!" there was also another time, when her father was disciplining her brother because he failed 2 cles. But my friend felt bad for her brother so she went up to her father and swore at him and yelled at him..(im not even gonna write what she said, its disgusting and rude).How do i tell her and knock some sense into her? by the way, whenever i get in trouble by my parents, she tells me i should yell at them too cuz i also have a right to my opinion (yes, thats her excuse for everything)