Teachers, what is the worst insult you have directed towards a student in your class?

I am not a teacher but this is what I'm talking about. My first college I was conditionally accepted, which meant I had to attend one of their summer school sessions, and pass the classes I took in order to be formally accepted to the college.

One of the classes was more or less an English class, by which I mean we spent an entire week talking/arguing/debating/discussing the Stanford Prison and Milgrim Experiments which didn't really belong in an English class but whatever. I also fell in love with the professor, in the sense of how they presented the class to me. So I signed up for every class of theirs I could which meant four classes in total; the summer class, one in the fall and two in spring.

At the end of the year I got my last paper back form this professor and on the last page they had my grade C-/D+ and the following comment/insult: "I am saddened and DEEPLY disappointed in the obvious fact that despite your now having been in college for an entire year it is quite obvious that you have yet to master, grasp or even begin to understand even the most basic concepts and skills needed to write successfully in college."

All of that was true, but it still hurt because they were essentially saying, "Get the FUCK out of here you don't belong in college," which was also more or less true.

I had very little idea about what 'critical thinking' was or what it meant or how you did it, which was pretty much what the professor was circling around with their comment.

That is the kind of insult I'm talking about.