…but surely somebody did:

Almost, but not quite, up there with those
Metal Men t-shirts in the “not really explaining what all this is about” department. Though I guess that’s probably the point of wearing a shirt like this…the right people will
know, man.
Hey, remember that time in the ’80s when Howard Chaykin did an adult-themed Blackhawk mini-series, and it was relatively popular and there were follow-up Blackhawk comics by other creators that were also adult-ish and slightly naughty and they were still getting enough attention that DC actually produced a little bit of point-of-sale signage to tell everyone “hey, Blackhawk’s in our weekly anthology book?”

And there it is. There’s tape residue on the back, so this sign was up at the shop at
some point. Hopefully when the book was coming out in 1988, and not, say, in 1993.
I’m pretty sure this next bit of comics retail detritus, dated 1987, was intended to get names and addresses for store mailing lists…at least, that’s how it should have been used:

In case you can’t read the text:
“We the undersigned, wish to voice our opinion as guaranteed by the first amendment. The Mutant Registration Act as outlined by the government must be repealed if we are to maintain our freedoms as specified in the Constitution.”
Pretty sure “First Amendment” is supposed to be capitalized. Also, has the Mutant Registration Act been repealed yet? I haven’t been keeping up.