We're getting a bit hung up here on "copy is included in UX" and ignoring the actual situation here I think.
The question, as originally asked, was certainly not a matter of copy:
why we using the word OOPS if something went to wrong in the sentence or communication with others?
I would like to know the correct information regarding this question. Any help would be much appreciated.
It was a question asking about the usage of english in general with no apparent tie to UX or use in a user-facing manner. The accepted answer drives this point home, it is entirely factoids about the origin of the phrase and absolutely meaningless in terms of UX.
This is not a question about writing copy:
What is the origin of the phrase "raise the roof"?
This is a question about writing copy:
Is it appropriate to use the phrase "raise the roof" in a marketing site for an enterprise app?
Now the question is reopened for some reason, and we're in a bit of a nasty state; the question is asking for UX answers and currently has a +6 accepted answer that is explicitly an English lesson and no more relevant to UX than "don't set users on fire" is relevant to UX.
Personally I think the question should be reverted to it's original state, migrated to English (if they want it, seems in-line to me) and, if anyone cares to know the answer, the edited version should be asked as a separate question, where it can remain on UX. I don't really feel comfortable with the edited question and deleting the now non-answer that was originally accepted, because the question has clearly changed entirely in it's intent.