A usually silent emission of gas when endeavoring the weekly shopping rounds. One can be both a victim, or a perpetrator of a mart fart. The presence of multiple people in the shopping mart environment, makes it the ideal place to fart and not be the obvious farter.
Ralph was walking down the cereal aisle, and walked right into a mart fart cloud. Since no one was on the aisle but him, it must've seeped through the boxes from the juice aisle.
by Bada Bing, Bada Boom July 24, 2013