A loud fart, lasting several seconds, sounding much like someone ripping apart a large sheet of canvas. It can be smelly or benign, wet or dry. It gains it's distinctive sound and volume by being expelled under great intestinal pressure, with the pucker-string pulled as tight as possible. Over-weight people often must reach around and separate the cheeks prior to release, in order to reduce any restriction of flow.
Every morning, dad would walk down the hallway to my room, kick open the door, hyke up one leg, and wake me up with his morning canvas ripper.