your answer should be: ah ok, then I go to the other bar across the street. They accept BTC. Let me know when you will be interested and I will help you with.

I know the feeling, but never give up keep asking everywhere you go! The barista in this case got the idea seed in his head, next time he will wander why so many people are into it and he will self orange pill.

Next time maybe start with: hey do you accept Bitcoin? If they said no, then you say why, but it's so simple to create a Bitcoin wallet.

If they still being uninterested, then try @darthcoin's trick.

No cash? Ok goodbye.