You've all read New Teen Titans #16 and Captain Carrot and his Amazing Zoo Crew # 1 in which Superman travels to Earth-C for the first time and meets up with Captain Carrot and eventually the rest of the Zoo Crew. If you haven't, what the heck are you even doing on this page?
Is this the first time Superman, or a Superman, has been to Earth-C? This little tidbit I found today says otherwise.
The panels above appeared in Funny Stuff #22 (June 1947) and shows the Golden-Age Superman cameoing in the "The Dodo and the Frog" strip that was featured in that issue. The Dodo and the Frog, as every CCAHAZC fan knows, would later appear in Captain Carrot #3, with the Frog turning out to be the villain of that issue, Frogzilla. (Oops, SPOILERS!!! Yeah right.)
Like I said, just thought this was interesting, and it was something I was previously unaware of.
Make of it what you will.