I think it's just about that one guy (or girl) who is lying no matter what they're saying. Nobody takes them seriously, and every time they open their mouth, all of their friends exchange glances or elbow each other or roll their eyes or whatever. I had a friend like this when I was growing up. I think the narrator has finally gotten so frustrated with this person, that she's telling them exactly what everyone thinks about him/her. The music makes the song sound sort of confrontational.
I think it's just about that one guy (or girl) who is lying no matter what they're saying. Nobody takes them seriously, and every time they open their mouth, all of their friends exchange glances or elbow each other or roll their eyes or whatever. I had a friend like this when I was growing up. I think the narrator has finally gotten so frustrated with this person, that she's telling them exactly what everyone thinks about him/her. The music makes the song sound sort of confrontational.