I've used the Car Talk Puzzler linked above in past years. This year I decided to add a personal spin to the story. I changed the girl in the story to a girl I knew in high school. She had a bad accident in her Pontiac Fiero and then her dad bought her a Suburban. I used her as the example in the story totally changing all the details to match the puzzler but embellishing it with details from my high school experience.
A good friend of mine uses stories from his personal life all the time to help teach physics. When I've been in PD sessions he runs he breaks them out and they are great. They are entertaining and very engaging. He paints pictures you can see and then references the characters while making points long after he's finished his narrative. It looks like a powerful teaching tool.
In my example of this I have some moral pangs about changing history in order to teach physics. Is it ok to totally change a story and the present it as true in order to teach?