Recognised shorthand on the Usenet group comp.std.c for any
unexpected behaviour 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.
