"Suck my Dukakis!"
My friend Connor and I fashioned the "Suck my" on paper and magic marker taping over the original sign, the phrasing of which I can't remember, but I'm guessing "Commie Dukakis" or "Down with Dukakis". We pushed the sign into the vent so my Dad's friend Dean could see it. We giggled until he came around the house, screamed at us, and probably wished my dad wasn't some hippie peacenik type so he could beat the shit out of us. Quite frankly, he probably should have and saved the world some trouble... It was 1989. I was eight and already knew how to offend someone like a proper adult.
The sign was cardboard, nailed onto a 6ft long 2x4" along with a 1/2 dozen other signs. I don't exactly remember them, but here are some guesses: "Nuke Iran", "CIA! CIA", "Better dead than Red", etc. etc. It was part of my dad's attempt at political theatre.