Aigoo!
If you are referred to this page by a search engine, you are probably looking for the definition of the term 'aigoo'.
So, what does "aigoo" mean?
The word "Aigoo" has somehow become the common writing for Korean expression 아이구 "Aigu!" over the Internet. "Aigu!" is pretty much equal to "Oh my (God)!" in English. An Sonjae explained in his article "Literary Translation from Korean into English: A Study in Criteria" where this expression could be used:
Thus the exclamation 아이구 "Aigu!" is used, with varying tonality, in keening for a dead parent, or expressing sympathy for another person's bad news, but it is also used on spilling a cup of coffee, or to express exasperation on just missing a bus, amazement on meeting a long-lost friend, or fury at losing one's job.