This guy was listening to either a teeny, tiny boom-box, or seriously damaging his ears with his headphones. Either way, he was playing music that was audible to everyone on the bus. And this girl says, "I don't mean to be a bitch but could you turn that down?" And the guy does, and the next minute the girl gets on her phone and talks loud enough for the whole bus to know she's not getting along with her boss at work. So either she wanted him to turn down the music so she could hear her telephone call, or she didn't quite get the irony of the situation.
As a side note, I'm surprised the bus driver didn't say anything to the boom-box guy. She's usually a real hard ass and won't take any shit. She's so tough that I panic if I can't get my bus pass out of my wallet quick enough, I'm always afraid she's gonna drive off without me.