David Letterman had a guest on who saw a photo of a steak that was exactly the way he likes it. So he had the photo laminated and carries it in his wallet. When he orders steak he pulls it out and says to the server "this is how I want my steak cooked. What is that called here"/ Except for once when the chef told him to leave, he always gets his steak perfect.
I think that is both hilarious and genius. .
Even better you could load the photo on your phone.