The ancient Latin term for a n00b during the days of the Roman Empire. It now can be used to describe someone of maximum noobic proportions.
Emperor Nero was total noobus maximus.
Kid 1: I just failed my basic English class.
Kid 2: You're a noobus maximus.
When someone is being the biggest n00b they could possibly be. Often used to insult inexperienced users when they fuck up big time while playing an online computer game.
DragonMan32: *shoots own teammate*
Renegade: omfg, Noobus Maximus! You want to shoot the RED people!