A childhood belief about general

I hardly ever used to clean my teeth as a young child (a habit I've not exactly grown out of) so when one of my milk teeth fell out, my Mum would tell me to put it under my pillow and the tooth fairy would come and exchange it for something.

Now, my Mum obviously knew I didn't clean my teeth very much, because every time I did this, instead of there being a nice shiny 50p underneath my pillow in the morning, there was usually a really old, rusty, old penny that could never have been used anywhere.

I'm surprised it didn't make me clean my teeth more!