VEHICLE WAS PARKED AND ENGINE OFF AND KIDS WERE GETTING INTO CAR WHEN ONE OF THE KIDS PULLED IN THE SHIFTER AND SHIFTED THE VEHICLE INTO GEAR. THE VEHICLE BEGAN TO ROLL. THE SUBURBAN WAS STOPPED WHEN IT HIT ANOTHER VEHICLE PARKED BEHIND. THE SLOPE WAS SMALL AND THE IMPACT WAS INCONSEQUENTIAL. UPON FURTHER INSPECTION IT WAS FOUND THE VEHICLE CAN BE SHIFTED IN/OUT OF PARK WITH OR WITHOUT KEYS IN THE VEHICLE AND THE VEHICLE IN THE OFF POSITION. THIS EVENT COULD HAVE BEEN CATASTROPHIC, HAD A CHILD BEEN BEHIND THE VEHICLE WHEN IT CAME OUT OF PARK AND INTO GEAR. WE HAVE VIDEO OF THE VEHICLE BEING ABLE TO BE SHIFTED WITHOUT THE FOOT ON THE BRAKE OR THE VEHICLE RUNNING.