"Really, really
cool". For those situations for which mere "cool" isn't enough.
Some people insists using this form of word, mixture of German and English. Perharps German prefix sounds confusing to others, or perharps the prefix has some additional connotations I'm not quite aware of. I don't speak German, and the dictionary would translate that as "over-cool" or something. No idea. Sounds cool, though.
See also: Quidquid latine dictum sit, altum viditur