Our family was once all together on a holiday at St Helens in Tasmania. It was a good holiday and everyone was in a fine mood. Apart from when Dad lost the keys to the cottage and the car, and had to break the window of the cottage to retrieve the other set of keys, the McQueen family was having a remarkably successful holiday (we never did find the keys).

One evening, Penny was beginning her evening rituals, which included brushing her teeth. She couldn’t locate any toothpaste, and asked me if I had any of my own that she might borrow.

“Sure, I’ve got some,” I said. I went to my supplies and came face-to-face with two tubes: toothpaste, and shaving cream. In a rare case of brilliant thinking, of grasping a golden opportunity, and not a small amount of deviousness, I selected the shaving cream and handed it to Penny.

I was full of naughty glee. I watched and hoped, trying to suppress a grin. I knew Penny was well able to read at this stage, but I thought the label on the tube might escape her notice.

Indeed it did, and Penny loaded her toothbrush with the paste, shoved it in her mouth, and started scrubbing away. Two seconds… five seconds… her mouth started filling up with foam, and her pace slowed slightly. She frowned, beginning to perceive that something was not quite normal, and stopped. Then she saw me burst out laughing and she realised. She had a closer look at the tube I had given her.

“I thought it tasted a bit weird!” she exclaimed, belatedly, with a mouthful of froth. She ran to the sink and spent several minutes giving her mouth a good rinse. I yielded to slight remorse, and gave her a more conventional tube of toothpaste. Overall, she took it very well and thought it was very funny too. But she hasn’t got me back yet, so I’m hoping she’s not still planning something really good.