Grandma, you know the treasure chest...

"The green one with the cute tassel for you to open it?"
"yes, I know the one"
"Well, last year it was under the Christmas tree and..." She pauses and chooses her words carefully "I thought we could do it this year and we could put gold coins in there, like last year. I think Mummy has got some at our house."

And that, ladies and gentlemen, is how traditions are created.