I've known for a long time that the trend for making sure that every tiny aspect of a given super-hero has been canonically explained isn't exactly new - I'm sure that if bow ties had gone out of style before the Silver Age was done then we'd have even more explanations for why Barry Allen wears one - but I think that this one, from Superboy No 8, 1950, is both the earliest and most ridiculous that I've ever seen:
Not this part: though it is pretty ridiculous it does make sense to justify the fact that Superbaby wears a cape if you plan on writing a lot more Superbaby stories.
I will refrain from questioning the sanity of any decision that would result in more Superbaby in the world. It's done and that's that. All we can do is try to forgive the past.
No, this is what I was talking about. An origin for Superman standing with his arms folded.
An origin of Superman standing with his arms folded.