For example, I'd make a sticker with the text "Have you heard of Bitcoin?" instead of "I accept Bitcoin payments". "Have you heard of Bitcoin?" could be used ironically or non-ironically in many contexts. When someone complains about their bank, send a "Have you heard of Bitcoin?" sticker and it'll make the convo more interesting.
Nah... Tho it's a cool idea, I won't really agree with it. "Have you heard of bitcoin?" would make the person understand that your aim is telling him/her what bitcoin is. On the other hand, "I accept bitcoin" makes the person understand that bitcoin is a means of payment. And also, the person won't know that your main aim is to tell him/her about bitcoin. He/she would definitely ask you what you mean by bitcoin. And then, your pour it all out (remember to tell it's advantage over fiat. And of course, it's disadvantages).