Mu is another
way of saying moo. It is a subsitution of saying
any word or phrase. There can be an
almost complete conversation of just this word.
Bob: So I hear you
think Kristina is
hot?
// Jim Shakes head as to say no.
Jim: Mu!
// Bob makes a look as to say "Why not?"
Bob: Mu?
// Jim makes a mater-of-factly look.
Jim: Mu!
// Bob makes an understanding look.
Bob: Mu.