I have two answers for this, I'll post them separately.
It was my senior year and I had to drop out due to family reasons. On my last day, I had to get all my teachers to write my final grade on this form I was given and they had to sign it... I knew what my grades were however because mid-term report cards came out the day before. I had straight A's.
I went to my Career class, this class allowed me to get out of school two periods early so I could work better hours. It was my last class of the day.
I never liked the teacher though, a lot of the teens were in the class because they had gotten pregnant young, were living on their own, and needed to get out early to support themselves. This bitch of a teacher kicked 4 young mothers (all 18 or older) out of my class alone because they lived on their own and weren't able to get their parents to sign things because they had cut them off.
(I mean, these poor young mothers, struggling to hold a job, raise a child, and STILL committed to getting their diploma... It takes a special brand of cunt to kick them out of a class they desperately need.)
During the first 15 minutes of the class the teacher explained we had a new project that would count for 50% of our grade. Considering it was my last day, I didn't need to do it.
There were guest speakers that day to talk about career choices. When they stood up to speak and my teacher sat down, I went to her desk and showed her the form. She asked me why I was dropping out and I told her it was none of her business.
She squinted at me and said, "Well then, I suppose your grade is none of your business." and shoved the paper back to me.
I handed it back to her and said, "Look, mid-terms came out yesterday, I know I have an A. Could you please just write it and sign it so I can go home?"
She took the paper and wrote a big, red F. I flipped, I asked why the hell she would put an F on there and she says, "I just assigned you a project today and you wont be completing it, so you get an F."
I shove the paper in her face and say, "Re-write the grade." She says no and stands up.
I get really close to her face with the paper pressed against the side of her head and say, "RE-WRITE THE FUCKING GRADE."
She says no and walks over to her second desk.
I pick up a chair and chuck it at the wall and scream, "Look, BITCH! Don't be a fucking cunt! RE-WRITE THE GOD DAMN GRADE!"
She picks up her phone and calls campus security and says she has a violent student and needs assistance.
I say, "OH GO FUCK YOURSELF!" Grab my stuff and start walking down the hall.
The principal comes running down the hall with his walkie-talkie and I say, "Mr. FXXXXX, you don't need to run." He barely looks at me and says, "I have an emergency!" I shout to him, "YEAH! I'm the emergency!"
He stops and comes back over to me, the security guards come running up and he stops them. I tell them exactly what happened. Principal takes my paper and tells me to hang tight with the security guards, so I pull out my crossword and they both help me with it.
Principal comes back with an A on my paper and lets me watch TV in his office till the bell rings.