Was the joke in that book? I'm pretty sure I've never read it, and I remember coming up with the joke.

Early 80s, I think. "All syllogisms" was one of my first mass-produced button slogans-- the business was started in 1977, but I took some years to start mass producing slogans.

My printing records say that I did 3 print runs in 1988, but that plausibly means that I had been selling the button for a while because I don't think I was doing 3 print runs at a time.