First made a Bizzare appearance in the movie "Knowing". It just ran out, galloping and making the most funniest moose-like sound possible, giving "Knowing" one of the movie moments in history.
You can also use that term if you have nothing better to say and want people to laugh.
"Did you see that Flaming Moose during the burning forest scene in "Knowing"..that was some funny shit!"
Person 1: so...what now..anything...
Person 2: Flaming Moose!
Person 1: HAHAHAHA!