First of all, I'm sorry that you experienced that, you did not deserve to be humiliated, in fact, no one deserves to be humiliated like that. I'm more disappointed with your professor though. In my Senior High back then, we have this recitation in class, I stuttered quite hard when it's my turn, some students start to "try to not laugh" face, and it's just so plain disrespectful, but our teacher defended me, and even paused the whole class and addressed those people. I'm a joker/sarcastic fun kind of person, but I have one golden rule: Never joke about people's appearance, mistakes, or their insecurities. I experienced the receiving end of it and I don't want people to experience what I felt.