The impressions we make as instructors of physics can affect student learning and public perception of physics teachers, physics as an academic subject, and physics as a profession. There are many sources from which we can collect evidence of these impressions. Among these sources are online public forums such as those at the Internet site known as YouTube. Whether we are proud of these impressions we make or not, we should consider how constructive these impressions are for our students' physics learning and their impact on the public perception of physics and the community of physicists.