When a student decides to act like a racist jackass during a lecture. There was a time where I was attending a presentation in regards to how Civil Rights is still being fought after the Civil War to present day, with the rest of my class, and there was a full-blown white supremacist that kept interrupting, bringing some insane talking points (that are very similar to those right-wing views) and the sort.
Everyone in the room was practically embarrassed at this clown was trying this hard to disrupt the lecture, but all it did was prove the point of the presentations. When any discussion towards racism in this country, the bad actors come out in full force to downplay (and defend it). Utterly disgusting behavior.