Many years ago, I drove a truck for a living. I often worked on Saturdays with my friend, who also worked there, too.
One such Saturday, we had to wash the trucks behind the building. Afterwards, the trucks had to be moved around front, where they were parked until Monday.
I washed the big one, which had air brakes. Without getting too much into details, it takes a while after washing and doing some minor stuff to the air brakes, for the truck to be safe to drive. The air pressure has to build back up, essentially.
So, I started the truck, and hung out and waited. My friend was in a hurry, so he wanted me to move the truck.
Nope, the warning buzzer is still, erm, warning.
He assured me that a real truck driver can handle a situation like that, and he jumped up into the truck. I headed into the office.
The next thing I heard sounded a lot like a large truck crushing a Buick, because, well, a large truck with no brakes couldn't stop, and crushed a Buick.
I was out of the shop and on the scene in a few seconds. My buddy was still sitting in the seat, and was kind of stunned. I got up in the other side of the truck and set the emergency brake. I told my friend, no matter what, tell everyone that he set the brake. He repeated the story so many times (to the police, to the insurance company, to the boss, to the Buick owner) that to this day, he believes that he did.
I always felt badly for the guy who owned the Buick. But thinking about it, I probably shouldn't have. He walked in to a clothing store to buy a suit, and wound up with a new car.
This also worked out ok for me. I sent the story in to a magazine a few years ago, and won a prize.
And my friend? He got a newer, better truck to drive.
It was win, win, win.