Bon Ami

 Here's a thing around Europe, so we had better get used to it.

You pay 1 euro to go to a public bathroom. This is usually paid at a vending machine next to the turnstile into the bathroom.

The receipt you get from the machine is called a bon.  Often it gives you a discount of equivalent value at the establishment. The one I got where we stopped for lunch gives a 1 euro discount for a coffee. 

So they encourage you to consume more liquid, so that you will spend another euro at the next bathroom. The ultimate perpetual motion machine or the circle of life? 

Probably neither, but it’s a great business model.

I just need to ask why it has an expiry date of 31-12-28. That just makes no sense.