I have been give a story in statistcis based on Independence and the Gambler's Error' and as part of my teachers training I have been asked to make same point but with different story to my learners of secondary school:

Here's a story:
uncle Jim hated flying. No matter how safe people told him it was, he was always worried that someone would have a bomb on the plane. Hs family doctor was little hlep so in desperation, he visited a statistician.
"tell me " he asked, " what are the chances that someone will have a bomb on a plane?"
The statistician looked through her tables and said,"A very small chance. Maybe one in a hundred thousand."
"so what are the odds of two people having a bomb on the same plane?"
"Extermely remote," she said "About one in ten billion."
Uncle Jim nodded and left her office. And after that day on, every time he flew , he took a bomb with him.

I had few brain stormin seesion and best I could come up with a boy hated chior- so he decided to maim- ask her sister what are the chances he would get caught- she said- one in 10 and what are the chances if two of us are maimimg - extermley remote she said one in 100- and ......

here I am missing the punch line- can't seem to progress.... please throw any ideas- thanks