A sight you didn't see everyday, even in Metropolis:
Now, there is a "rational" explanation:
See, Superman had been in space helping some aliens and...wait, what's happening?!?
SPOILER ALERT: It wasn't really Superman...it was a Superman robot created by Lex Luthor to steal some silver for aliens whose culture really really valued silver, while at the same time destroying Superman's reputation.
Or, in Silver Age terms, just another Monday.
But that's your assignment today, kids: steal something from a co-worker's desk (preferably something shiny) while chanting "Silver! Must have silver! Hee! Hee!"
From World's Finest #137 (1963), as reprinted in World's Finest #224 (1974)