My biggest pet peeve

My biggest pet peeve is when somebody unintentionally spits on my face when they talk to me. To show my respect, I usually stay there or just step backwards a little bit, because I know people may not be aware that they do this when they speak excitedly. I really don’t want to discourage and insult them by keeping my distance but it can be quite annoying. I remember when I was in senior high school, my Chinese instructor, a 50 years old guy, spit a lot onto the blackboard while speaking. He spit so much, and often, that the blackboard was wet afterwards.