"Oops" is usually said by someone who is the biggest fuckup known to humankind at a certain point in time. It is usually accompanied by a weak smile, a fluttering of eyelashes and a few mangled bodies laying around in a landscape of complete destruction.
Note that the utterance of this word is neither an apology or acknowledgment of guilt. It does call attention to whatever idiotic thing the dumbshit in question has done as a point of pride. This could have been easily handled otherwise by Captain Obvious. However, you cannot ignore the comment as the fucktard may have done something that will soon be fatal to you. Some think the word should be appreciated for giving a warning, but if you were smart, you would kill Mr. or Ms. Oopsie and run like hell as far away as possible.