At least a couple times, yeah, I've signed something after using AP. Might have been an electronic signature on the terminal.Sign? Genuine question, if you use AP in the US do you have to sign as well? Here in the UK I absolutely cannot remember the last time I had to sign for payment, it is one thing I feel they've got right with chip & PIN.
I don't sign my credit or debit cards anymore, either. I write, "CHECK I.D." with a Sharpie on the back. I don't know if it changes the clerk's routine, but at least they go for a name confirmation.
I heard a story about a guy who endorsed his checks with "Mickey Mouse" to see if anyone would catch on. Nobody did, much to his annoyance.