What is O Blaargagg!?!?
The act of forgetting what to say or not knowing the proper response to a question. When this happends you simply yell "O BLAARGAGG?!?" and run away screaming.
Brendon: Hey Ryan, did you know Gears of War is coming out tommorow?!
Ryan: O BLAARGAGG!?! ~Runs away~