When you are the passenger in a motor vehicle, you may only pull the emergency brake when:
The driver is having an epileptic seizure, or is otherwise incapacitated.
How will you know that the driver has become in-valid?
The driver may be shaking in an uncontrolled, spasmodic way.
The head of the driver may be banging against the steering wheel or head-rest of the driver's seat.
There may be drool or spittle issuing from the side of the driver's mouth.
The driver may be making agitated, moaning or groaning noises.
The eyes of the driver may have rolled back in the driver's head.
The vehicle may appear to be out of control, or swerving into oncoming traffic.
Conversely, the driver may not be moving at all, having slumped in an unconscious manner, seemingly unresponsive to a prod in the ribs.
Never, ever, under any other circumstances, even if you have your learner's license, have had prodigious experience on various computer or video driving games, and think you are mature for a fifteen year old male will you reach down and pull the emergency brake.
Never, ever, ever again.
Have we made ourselves clear?