yes, I am saying that my professors did it to me when I was a student
I pass written exam and came to take oral exam after that ( it was mandatory)
he gave me 7 problems (all theorems and proofs), sat on my desk watching me do it
when I was on last question, on very line before last one I put - instead of +, and he say " that is wrong colleague"
it took me a second to realize mistake and I corrected it immediately, but he said "sorry, see you next time"
