Might be kind of obvious, but professors who list off literally ALL of their past accomplishments upon introducing themselves to the class. It's vaguely impressive that you wrote 7 books on the history of upstate NY's health care facilities, it really is...but to physically bring them in and read excerpts from them is desperate. I don't mind anyone sharing some personal stuff and even a few credentials...it can put everyone at ease, but honestly...have some dignity. This also goes for students who feel the need to mention 40 times that they're double majoring in History and Japanese while maintaining a 3.5 average. Keep it to yourself.
Also, English professors (not sure if this is familiar to other English majors), save the dramatic, self-important diatribes about the endless sea of opportunity getting an English degree opens us up to. It's true that it's a broad subject and does present you with a bunch more options than your average major, but you cannot be an astronaut with an English degree alone. The one person you have in mind who became an astronaut with an English degree would've became and astronaut without it, and by no means represents the average English major. Keep it to yourself.