Erroneous and foolish use of a German grammatical rule to pluralise "Xbox". Arises from the geek-chic use of language where they refer to multiples of Unix computers as "boxen" instead of the correct "boxes". This misappropriation conveniently ignores the fact that an Xbox is not a Unix machine at all, but rather a vastly overpriced, repackaged PC of moderate ability circa 2001.
There shouldn't be any examples of this word in use.
n. pl. The plural form of xbox.
"Still, there was less shame in a casual day of Goldeneye with mates
than hulking 4 Xboxen and TVs together in a room full of geeks".