A Patty Mag is when you take an unexpected or unplanned dump in your pants in a social environment. It is similar to a "shart" only more intense in duration and public awareness.
Man, I was in line at the bank when this chick pulled a sweet Patty Mag at the check out counter. Everyone in the place gave her a round of applause and then ran out of the building in disgust.
by san-d-mag February 05, 2010