Omgoosh originated from the the phrase "oh-my-god" but has recently been interpreted as "omgoosh".
The origin of this is thought to be a group of kids in Gloucester trying to talk using shorthand.
"Omgoosh, what the fuck was dat?"

similar examples:
WTF = wut-fa?
OMG = Omgoosh
BRB = Burb
by shakey June 18, 2004
Get the omgoosh mug.