Stick with me...
There is a restaurant in Naperville that makes a coffee encrusted filet (or maybe ribeye).
It is kind of a pepper/coffee crust. I've tried it a couple times at home with mixed results. I think the key is more pepper than coffee. The ground coffee makes it 'dry'.
I would say - one part course ground coffee to 3 parts fresh ground pepper. Equal parts is too much coffee. Slather with olive oil - rub in coffee/pepper mix. I've had better results on the grill than pan seared.
Of course - if they don't like pepper or coffee - this is a BAD idea.