This happened during my first semester of college two years ago. There was a girl in my class who never talked to the teacher. He would ask her questions, but she stayed silent. I can’t remember her making any noise at all.
One day, the teacher got very angry. He thought she was ignoring him and being rude, so he shouted, “Hey! Didn’t anyone teach you how to speak?” She stood up, walked to the whiteboard, took his marker, and wrote, “I am mute, you fool.