I'm a bit hesitant about "uber", because it seems to be listed as a prefix rather than a word in its own right. I can see some evidence that people are starting to use it as a word - I saw a Web page where someone said, "This macro is positively uber!" But is this an emerging usage, or just an isolated ideosyncracy?
I have no hesitation, however, about "fubar". It's in a few dictionaries, including the Oxford, so it should be allowed. ("Snafu", incidentally, is already in the word list; in fact, it's classed as common. "Very common!" I hear some of you say.) I'm not sure if "mubar" was being put forward as a suggestion - it does seem to be used a little, but almost always in capitals at this stage, so I don't feel it qualifies for Chi.