I was recently given this as change after I bought a Diet Coke at a store. It looks a lot like a dime, but it's actually a vintage half-franc coin from pre-euro France. I decided the blog post was worth more than ten cents to me, so I didn't complain.
* CORRECTION: Kaspar Enz observes that this is actually a Swiss half-franc coin and has nothing to do with France. I let my desire for a timely post get in the way of reality.