Chez–you did right, GQ was probably OK for starting this thread. But I’m moving it to ATMB just so people who might know the answer are more likely to find it. At least, IMHO.
To follow up on that with a question of my own–I’ve seen a copy of the Chicago Reader, but I didn’t even bother to notice that there was/was not a banner with these sayings.
The Chicago Reader online archives carry Cecil’s columns from January 1988 to the back end of 2007.
Here’s one from 1988 (in which the author briefly discusses the coefficient of drag while swimming nude) and the taglines are absent. It’s just possible they are stripped from the article for archiving purposes but I’m now equally curious to know the answer to Sam’s question.
As near as I can recall, I wrote this slogan for the T-shirts we started selling when the Straight Dope began appearing on America Online in 1995. Matt Jetmore, who ran a separate Straight Dope website at the time with our permission, picked it up at some point for the home page we took over when AOL kicked us out around 1999. It’s one of only two things I have ever written that Cecil has liked, the other being Perfect Master, his user title on the SDMB.