If you're driving along and want to stop for the traffic lights, you start decelerating. The car in front of you slams the brakes and leaves less space then you

If you're driving along and want to stop for the traffic lights, you start decelerating. The car in front of you slams the brakes and leaves less space then you anticipated. You now need to decelerate faster. That's negative jerk. If you apply the change in deceleration instantaneously, you will also experience jerkiness in your braking (= way to remember what this derivative is called).