Recognized shorthand on the Usenet group comp.std.c for any unexpected behavior of a C
compiler on encountering an undefined construct. During a discussion on
that group in early 1992, a regular remarked When the compiler
encounters [a given undefined construct] it is legal for it to make demons
fly out of your nose
(the implication is that the compiler may
choose any arbitrarily bizarre way to interpret the code without violating
the ANSI C standard). Someone else followed up with a reference to
nasal demons
, which quickly became established. The
original post is web-accessible at http://groups.google.com/groups?hl=en&selm=10195%40ksr.com.