Just remember those who teach do so because they could never make it in the real world!
Many years ago, 1981 to be exact, my grade 8 teacher (maude) Mrs. Rogers pulled that crap on me. Okay, she went back to teaching and I went back to her desk, sat in her chair and pissed like a race horse in her garbage can, adjusted and zipped up, took her water bottle and washed my hands. As I was walking out of her classroom I said, "Told you I had to go!"
The next day, my parents went to the school and my father's exact words to the teacher were: "Are you a fucking idiot!"
I should have pissed in her purse!