Mung is the angle of attack of a disc. Wing up being positive mung, wing down being negative. Mung creates additional drag and/or additional lift on the disc creating a stalling effect that leverages speed and spin into lift. It is employed to float and hover discs at a distance.
Mung plays a large role in air bounces and floaters and is a critical attribute in disc dog freestyle and games.
Mung, positive or negative, is not a desirable trait in distance throwing with light plastic.