Hi. What you do is you either a) learn to be more tolerant of the fact that neurodiversity is a thing that exists and accept your friend for who he is, stutter and all; or b) break off your friendship with this guy for his sake. I’m going to give you the benefit of the doubt and assume you didn’t mean to be as ignorant or disrespectful as your post came off as.  Stuttering is a neurophysiological condition that can’t be prevented just by “thinking about what you want to say before starting a sentence.” He can’t help that he stutters. If you have to “take deep breaths and chill out” simply because he repeats himself—mind you, I mean no disrespect by this—*you* need to learn to be patient and realize that there are bigger things in this world to be upset about than your friend’s speech.  The fact that he doesn’t seem to mind his stutter is such an incredible thing. So many of us who stutter have spent YEARS of our lives trying to accept ourselves. To thrive despite the ridicule. The mocking. The bullying. The teasing. The offhand comments. The unsolicited advice. The *impatience*.  Please, if this friendship is really something you value and wish to have in your life, educate yourself. Slow down some patience for your friend. If you can’t do that, I advise you to distance yourself from him so that he may continue to be the flourishing and self-accepting individual he seems to be. Do not ruin his self esteem by being so woefully ignorant to the reality of stuttering.