My smart friend Beate found it and posted it to her wall, and I had to nick it and share it.
Translation: A coffee 2€. A coffee with a please, 1.80€.
Imagine a restaurant or coffee shop that operated entirely on this principle. If you say please and smile widely, and play nicely with the waitron and your fellow coffiers, then you get a little discount off the top. The world (or at least that coffee shop) would be a happier place for it.