We're not sure how he got out of this dilemma, as the show ended with him still in grave danger, but he seemed okay in the next episode.
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 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!