originating in Middletown, Rhode Island, O'Brien is arguably one of the worst math teachers to ever live. He style, looks, and personality are some of the worst you will ever see. His teaching style consists of going over the material until he remembers how to do it well enough to grade a quiz, then quizzing. Whether or not his students understand it means nothing to him, and for this reason he is possibly the most hated teacher on the whole Aquidnick Island.
Extremely fond of the number "0", as it is the only grade he enjoys giving.
Also known to creep on certain innocent girls through entire class periods/school years
Student A- Fuck man, I have O'Brien for Honors Algebra II!
Student B- Oh, dude, that blows. Enjoy failure...
O'Brien- So you put this here, and don't skip steps, OR ITS A ZERO! Oh wait, I did it wrong...and I skipped a step...ITS STILL A ZERO FOR YOU!
Student 1-Wait, I don't understand this, could you go over it?
O'Brien-NO! Quiz time!