Action 273 (Feb. 61) marks the first appearance of Mr. Mxyzptlk in this book. What, you cry, I have seen earlier blog posts about him! Why are you lying to me?
No, foolish mortal, you have seen blog posts about Mr. Mxyztplk not Mr. Mxyzptlk! Look closely if you cannot spot the difference. It’s really the only difference, aside from the suit, between the Golden and Silver Age versions of this character.
After a brief preamble with Mr. Mxyzptlk wreaking havoc on Earth and being tricked into saying his name backwards, Siegel and Plastino send Superman to the 5th Dimension, where he plays pranks on Mr. Mxyzptlk himself. Childishness is catching, it seems.
Still, it’s a fun variation on the theme. Mr. Mxyzptlk keeps trying to trick Superman into saying his name backwards. But when he succeeds, it does not work. Superman voluntarily goes back, by saying Kal-El backwards, the name is feels is his true name.