Oh My Bellamy.
This is taken from the name of Muse's frontman Matthew Bellamy.
All Musers (Muse fans) who exclaim something, instead of saying OMG (Oh My God) they say OMB.
Bieber fan #1: "OMB, she's wearing oversized sunglasses! Doesn't she know that Justin thinks they're overrated?"
Bieber fan #2 "And she's wearing ugg boots! This girl has no chance! He hates them!
It stands for Oh-my-Bacon. There were many reasons for this: 1) Canadians are awesome 2) its really catchy 3) created by girl who had a dream to spread this phrase. Hopefully this is going international :)