Shamefully, I found this link thru the deranged but hardworking Ann Althouse. The Zippy daily strip archives go back to 1994 and can be word-searched.
(Added value: Ronald Reagan just didn’t get Zippy’s brand of humor. Seriously, he said so and added that his favorite strips were Mary Worth and Apartment 3G. I learned this from a passage in Dutch by Edmund Morris that describes Reagan and Vice President Bush having lunch together. One of them, either Reagan or Bush, mimed jerking off during the lunch, as punctuation for some joke.)