Like a guitar, anal acoustics is caused by a loud sound erupting from deep within, forcing the sound out of the nearest exit, which then causes your body to perform anal acoustics. (results may vary.)
A person who's a very obnoxiousasshole. An anal flagger is someone who has passed the level of douchebag in their behavior and is headed for asshat status.
Steve: "Everyone hates Todd because he's so rude and obnoxious! He acts like such a douchebag!"
Ryan: "Yeah, Todd's a real anal flagger!"
An anal queef is the release of air from the anus after the penis has been removed from the anus after anal sex. Not to be confused with a common garden fart.