Marty Pasko returns as scripter, joining Swan and Chiaramonte for a bizarre story in Superman 349 (July 1980).
Coming back from a mission in space, Superman is puzzled to see that the Daily Planet staffers seem to have changed gender. Penny White is the editor, and he also sees Jenny Olsen and Louis Lane. When Superwoman shows up to save a person in danger, he suspects he may be in a parallel universe.
Investigating further, he sees that the Justice Leaguers have all switched genders, as have most of his villains. But his appearance draws the notice of this world’s heroes, who suspect him of being an evildoer.
Superman is not too sure that the parallel universe theory is correct, when he sees that Clara Kent is not the secret identity of Superwoman.
The greatest challenge he faces is Wonder Warrior, but he prevails over the male Amazon, stealing his lasso.
Because by this point, he has figured out that Mr. Mxyzptlk is behind this – the one person whose gender has not been changed. We do get it confirmed that Mxyzptlk’s marriage from his last appearance was annulled. But he is out this time to mess up Superman’s romantic life.
With the Wonder Warrior lasso, which functions the same way as Wonder Woman’s, Superman is able to force Mxyzptlk to head back to his own dimension, but the imp returns in a mere two months.