The Challenge of Retarded Superboy!
Given that his powers back then were pretty much limitless, I imagine it was pretty difficult for Silver Age Superman writers to come up with a problem that could actually provide enough of a conflict to get him through eleven pages. Fortunately, Jerry Siegel was able to find his way around this little problem back in 1959, finally answering the question as to how exactly one challenges a completely indestructable hero who can fly through the time barrier and move planets with his bare hands.
You make him fight a younger, completely idiotic version of himself.
The whole thing goes down in a daring tale called "The Revenge of Luthor" from Action Comics #259--conveniently available in crisp, monochromatic glory as part of Showcase Presents Superman v.2--and, as you might expect from a story where Superman fights his younger, developmentally subnormal counterpart, Red Kryptonite is involved.
Before we get into the story, a quick word about Red K, or as I like to call it, Plot Device #3: I think it's been made abundantly clear by now that I'm a pretty big fan of the outright wackiness of DC's Silver Age. But that stuff essentially amounts to carte blanche for Jerry Siegel and Otto Binder to weave pretty much whatever opium-fueled fever-dreams they wanted. Moreso than usual, I mean.
To be fair, though, it did provide me with one of my favorite moments of Legionnaire dicketry, when Supergirl flies through a cloud of the stuff and gets aged to an adult on her way to try out for the Legion, which goes a little something like this:
SATURN GIRL: So, Red Kryptonite made you old, huh? And how long does that last?
SUPERGIRL: I don't know... Couple hours, maybe?
SATURN GIRL: Yeah, have fun trying out next year, grandma.
SUPERGIRL: Aw, peas!
But anyway, back to Superman: The Red Kryptonite of this story shows up as a meteor that Superman grabs mere moments before it smacks into a passenger jet, immediately realizing his mistake and mentioning that he should've just blown it away with his super-breath. Which, yeah, pretty big mistake there, Clark. I'm pretty sure that if there were two things--and only two things--in the entire universe that could kill me, and one of them was a rock that comes from space, I'd make sure to check out pretty much every meteor I came across before I went over and grabbed it, especialy at a cruising altitude of 30,000 feet.
Fortunately, Superman has plenty of time to ponder the error of his ways as he plunges headlong into a conveniently-located field, all the while hallucinating the floating heads of friends and enemies orbiting around him, including a giant and incredibly disturbing Judy Garldand-esque Lois Lane that goes a long way towards explaining why those two wouldn't go ahead and tie the knot for another thirty-five years. Eventually, he shrugs it off and wakes up, only to be confronted by the reasonably shocking sight of Superboy standing there. And this, of course, presents somethign of a problem.
Quoth Superman: "But you can't exist at the same time as I do! You're me, as a youngster! You ceased to exist years ago, because I grew into an adult!" The fact that he says all that in a single word balloon leads me to believe that Red K has had the weird, unpredictable effect of making Superman speak in incredibly redundant expositions! Great Guns!
And oddly enough, that's not the only secondary effect that the Red K's had on Our Heroes, because really, plucking one's younger version of Superman out of the timestream without causing the entire universe to implode upon itself is just small potatoes compared to, say, giving him an ant head. That effect?
It has turned Superboy into a complete and utter moron.
Siegel makes a halfhearted attempt to set up Superman as having been afflicted by the Red K with a short temper, but by the time he gets around to dropping a scene like this...
...his frustrations seem pretty reasonable.
And things just go downhill from there, with Clark the Younger bumping into Clark the Elder and generally making a nuisance of himself, and eventually Lex Luthor devises a sinister Master Plan™ to turn the situation to his advantage by buliding a giant jungle gym out of Kryptonite (the regular green kind), and then putting a huge sign on it that says, in bold lettering, "LUTHOR TRAP TO CAPTURE SUPERBOY. ENTER HERE, PLEASE."
So, just how stupid is Superboy?
So stupid that even the narrator of the story turns against him. I mean, Luthor, you expect, but to actually have the captions break down and call him an idiot, that's a mean feat indeed.
Eventually, Luthor captures Superman as well (with a robot, naturally) and takes them both to a secret underground lair, where he's holding Lois and Lana captive in what I can only refer to as a Science Bubble, holding them hostage in a bid to make Supers Man and Boy fight each other to the death. It doesn't work of course because, y'know, they're invulnerable, so Luthor switches things over to Plan B, which involves Superman choosing between a locker containing Superboy (who will then be killed) and a locker containing a giant piece of Kryptonite (which will kill himself), thus begging the question as to why Luthor didn't just use the giant piece of Kryptonite in the first place.
Fortunately for all concerned (except Luthor, I guess), Superman finally snaps out of his Red Kryptonite trance and, of course wakes up from the crazy mixed-up dream he's been having for the last twelve pages and explains that he should've realized it was a dream all along, since, and I quote: "if Superboy really materalized, we would get along fine and make a great team!" Seriously, the ego on that guy sometimes...
So, for those of you keeping score at home, "The Revenge of Luthor," is both a dream and a hoax, and a Red Kryptonite story involving Retarded Superboy.
That's got to be some kind of record.