So when I got a new card, I got more explicit. "INVALID without photo ID," I wrote. The process has not changed. Exactly one person in the last year has carded me because of the strongly-worded statement. I have considered disputing every charge for which I'm not carded, since technically I indicated that I don't consent to the charge. But I doubt my credit union would be highly amused, and I would love to keep the 9% APR card I carry. (Not that the rate matters, since I've never carried a balance.)
The other thing I do is refuse to sign my name. Here's what I usually do on the signature line:
Most people think that's my thing. But, as with so many of "my" (or, I bet, "your") things, it's actually carried over from a non-mutual acquaintance. This habit I picked up from Jason Shenk when I was 18. We walked from campus to Marsh (or was it "Low Bill's" or whatever back then?) for some snacks, and that's how he signed.
So I often sign that way. Sometimes I draw something else. Sometimes it's random scribbles. Once I just drew an opaque rectangle. Sometimes I write "No way!" I get bolder, too, when it's one of those electronic key things. I do it because I find it annoying that there's no security with this stuff, and this is how introverted comedians express their frustration.
Today at Safeway, I did the usual. Unusually, though, the cashier looked at the receipt after it printed out. Squinted carefully at it. And then called me by name (my last name) as he wished me a good day.
Still no reaction to the drawings.