When your stomach, or intestines, make a sound that resembles a fart.

To be a true stomach fart, you must feel it happening

Invented in Borat's movie. It is said, when something great happens.

The growling sound your stomach makes when you're hungry and haven't eaten in a while. Sounds like your ass cheeks are attempting to squelch a wet fart on it's way out your ass hole. Stomach farts don't smell like anything, but they sound eerily similar to real farts and are actually much harder to conceal. Comparable to the sound of a blue whale's mating call; stomach farts are known to be exceptionally loud during test days and moments of silence.