When the fatty tissue of an individual's lower back is pressed together by the waste belt of their trousers, giving the appearance of an abnormally long
anal cleft, or "Bonus Butt".
The phenomenon is frequently observed when an overweight
individual leans forward while wearing a short T'shirt. Bonus Butt sightings are often reported at Ikea and other discount furniture stores, where the obese can be seen plopping and
rolling around on various furniture items.