You shouldn't humiliate teachers in front of the whole class.
Charlie is a high school student.
Charlie wants to have some fun.
Charlie tells a good pun related to the lesson the teacher is going over.
Charlie mocks their teacher's voice and posture and yells over them to get attention.
Everyone in the class laughs and the teacher appreciates Charlie's wit.
The students laugh, the teacher is humiliated, and the class is disrupted.