(n.) the second largest city in the Earth Kingdom (second only to Ba Sing Se), one of the last great strongholds of the Earth Kingdom during the Hundred Year War.
(v.) to steal, usually in a manner that is very unexpected or surprisingly (often without fighting); to conquer, usually in a comedic manner. Note: the act of omashu-ing is often accidental and unintended by the do-er. This is often accompanied by lots of confusion, especially by the do-er, and potential laughter (most commonly in recollections of the fact and from outside viewers).
(Most often done by Zuko in MuffinLance's stories on ArchiveOfOurOwn.)
Zuko omashu-ed Omashu by challenging Aang to an Agni Kai-- upon his victory, the Fire Nation gained control of Omashu.
"Oh my stinking hell/heck"
Something teenage girls or guys with no life seem to really enjoy saying. Usually only heard by people who think they're cool, but are really not. This is very popular on MySpace, FaceBook, online games, or other things like that.
Comment on YouTube: "OMSH, that vid was so cool!"
Reply comment: "Are you a 13yr old girl?"
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Kid on WoW: "OMSH, I just killed some Alliance guy who was 7 lvl's higher than me! I'm so 1337"
Guy on WoW: "Wow, you should just log and never come back."
Derived from the modern gaming term "hacks" or "hax". It is sandwiched in between two commonly know chatroom linguistics. "Omg" refers to the person becoming depressed or shocked in any manner. "Hax" refers to the situation or object being indescribably beyod ones imagination and "lol" is added to lighten the mood of the entire phrase.