I think thats not the point here. I'm sure you can find pissed off people even you give them gold. Let them be pissed of. Its primary to promote bitcoin, if they are happy with it is up to them.

This is a really good idea. I would like to mention that the text on the coupon is quite clumsy.

A waitress usually dosen't know what openSource or Peer to Peer (P2P) means. So keep geek things out there and go for the common people. Thats the goal, that Bitcoin will become a customary, every day thing. Like our FIAT currency, we do not speak about the chemistry in the color thats printed on, or the composition of the paper thats made of. So I would suggest something like:

"Make worldwide payments on low fees with Bitcoin. This is a international crypto currency. No central authority or policy ist involved. It works direct from owner to customer."

This is only meant as example.

PS: And very important: "Bitcoin can be exchanged to your preferred currency!" or something like this.