A "moo" is a response or terminology for a made-up or random statement or word made reproaching a question or starting statement that may or may have nothing to with the subject matter at hand. 2 a way of avoidance of truth, or to throw your the questioner off i.e., sidetrack to new thought.
Subject 'A': "Darvskins where were you last night?"
Darvskins: "Back in Amsterdam we didn't think is was polite to put your elbows on your face"
Subject 'A': "What?"
Subject 'A': "Oh. . . Um, okay."
Subject 'A': "Stop that!"