I never heard the middle school orchestra director angrier than when one student ignored his instructions to get out her instrument and play along with the rest of us.
The director knocked over two music stands and exclaimed, "What did I tell you to do?!" The student repeated Mr. D.'s instructions but for good measure told him her mother thought she "should quit that @#&*ing violin!"
"I don't like that," the director responded. "If she says things like that, don't listen to her. Now, you apologize to the class for that."
The student gave the class an insincere apology while grinning. Before walking the student down to the principal's office, Mr. D. said to the rest of us, "I apologize to those of you who are trying to learn something."
I didn't blame the teacher for being frustrated. I still wonder how I would have reacted in that scenario if I'd been teaching.