Good parenting, at its finest.

Student: F*** that, piece of s*** (etc, etc)
Me: EXCUSE ME?
Student: Oh, it's okay Ms. S--it's just song lyrics.
Me: I don't care what it is, it's not appropriate language.
Student: Oh no, my mom says I can cuss as long as it's just song lyrics.
Me: I don't care what your mom says. You are not in your mother's house. You're in my classroom. That language is not appropriate for my classroom.
Student: Ugh, not like you don't cuss all the time.
Me: I don't.
Student: You don't? Awww, Ms. S, you're so cute! How old are you? Like, 20? Maybe when I'm 20 I won't cuss anymore either. That's a good goal.