noun - A function of anatomy, where one has attempted to retain stool for release at a more convenient time and place, moreover, is the backing up of one's plumbing system. Acronym for "Reverse Gut Flow", coming from the body eventually succumbing to the inward force. Sometimes characterized by a gurgling noise within one's gut.
I was on a date at Maggie's parents house, and couldn't use there bathroom. Halfway through dinner I got some major RGF, and everybody thought my stomach was growling.