Whilst staying with my mother I spied the following treasure on one of her shelves:-

It brought back the most awful memory for me of proudly showing it off at school during show and tell. I had found it whilst digging for treasure in the bottom of our garden and was utterly delighted, as you can imagine. Told everyone. Nobody actually believed me so I insisted that many other friends come and we all furiously dig for the treasure trove I was convinced was there. Nothing else was found.
It wasn’t until some months later that I found the exact same one in my mother’s jewellery box. It turned out to be “the other one”. Even then it took me a while to work out what had happened. That she’d actually hidden it in the garden for me to find. I suppose it was quite sweet really, but I was absolutely mortified. The disappointment and humiliation I felt in believing it to be real treasure was huge.
I suppose it’s rather like when you discover the truth about Father Christmas and the Easter Bunny. It proved to be so huge a let down for me that it has always made me cautious of what lies to tell my children ever since.
What memories of your parents “untruths” do you remember that affected you hugely I wonder?