When a person's trousers and lowered and fasted around the buttocks or just below them. Usually common in rude boys and people who live in certain areas and estates. Originated from a prison where all black men had their belts taken off them because one black man strangled a white man with his belt, this caused their trousers to lower as thay walked. This was then taken up by people outside.
O my God bruv, look at that brers low bats.