Here, camp counselor/fireside-chant leader Chris Carrabba orchestrates the collective catharsis of an audience of 100 lovelorn, bookwormish teens. ''You guys sound good. Don't be shy,'' he urges the makeshift chorus at one point on this live recording, MTV Unplugged v2.0. And they oblige with full-throated versions of their hero's brokenhearted hits that outshout the man's own whiny wails. Eerie and fanatical.