[common; generalized from J. Random Hacker]
Arbitrary; ordinary; any one; any old. ‘J. Random’ is often
prefixed to a noun to make a name out of it. It means roughly some particular or any specific one. “Would you let
J. Random Loser marry your daughter?” The most common uses are
‘J. Random Hacker’, ‘J. Random Loser’, and
‘J. Random Nerd’ (“Should J. Random Loser be allowed to
kill other peoples' processes?”), but it can be used simply as an
elaborate version of random in any sense.