Hey, Aldo Alvarez, this one's for you! (Lesson of the day for everyone else - flattery works, and I respond to requests.)
This one's a fairly obvious pun, based on the character's name. The guy in red is named 'Mon-El', you see. Get it? Days of the week? Ok, ok....
On to business, then - time to make with the funny. Let's go right to the origin.
I said, 'ORIGIN', laughing boy, not....never mind. Get your mind out of the gutter. You have to forgive the audience, folks - paint a lass blue and they get all sorts of ideas.
Where was I? Oh, right, origin story. Superboy:
Bad news - y'all know what kryptonite does to Superboy? Well, that's what lead does to Mon-El's people.
- discovers rocket ship crashing to Earth;
- rescues the amnesiac pilot;
- assumes (based on flimsy circumstantial evidence - and not a Congressional sub-committee in sight!) that said pilot must be his older brother;
- names the guy 'Mon-El' (based on the day of the week he crashed, and the Kryptonian family name);
- grows suspicious of Mon-El based on even more flimsy circumstantial evidence (there's more of that here than an entire season's worth of 'Three's Company'!); and,
- exposes him to massive quantities of lead as part of a scheme to expose the suspected fraud.
So, what do we have for the no-longer-amnesiac kid from Daxam, Johnny DC?
Well, Mon-El, behind Curtain Number 1, we have certain death, and behind Curtain Number 2, we have a thousand-year banishment to the Phantom Zone, where you can share a ghost-like existence with hundreds of Kryptonian criminals, while Superboy gets to grow up and have a wonderful life dating women with the initials L.L.!
Ain't old comic books a blast?
Special bonus science section!!!!!!
My brother tells me that "MONEL metal" is a Nickel-Copper-Iron alloy known for its strength and corrosion resistance. Maybe Mort Weisinger was an amateur metallurgist....