The following article contains spoilers from The Joker: The Man Who Stopped Laughing #4, on sale now from DC Comics.
The Joker is known for having wild adventures, but his most recent might be the strangest ever. In "Knocked Upside Down" from The Joker: The Man Who Stopped Laughing #4 (by Matthew Rosenberg, Francesco Francavilla, Tom Napolitano), the Joker is cursed by Zatanna after he makes a pass at her and ends up becoming pregnant with his own child. After successfully giving birth to a son, the two consider Zatanna to be the mother.
Aside from being one of the most disturbing Joker stories ever written, it also raises the important question of whether this event was canon or not. There is a lot of debate about how true these backup stories have been. As a result, the Joker having a son needs to be considered, as he does have one in some timelines.
How the Joker Became Pregnant
As with most of his backup stories, the Joker stuck his foot in his mouth around the wrong person. This time he fell for Zatanna, and when he said they would make beautiful babies together, Zatanna cursed him so that "No one else will ever have his baby". Unfortunately, in her anger and disgust at the Joker's attraction to her, Zatanna inadvertently caused the very thing she was trying to prevent. After leaving him face down in the mud, Joker accidentally consumed a good deal of it, and in the morning, discovered he was pregnant.
A later visit to Doctor Phosphorous resulted in a bizarre birthing process, as the Joker vomited all the mud he had consumed, which then became a small, malformed creature that he and his henchmen tried to kill. Shockingly, the creature then morphed into a miniature version of the Joker, becoming the son he was never supposed to have. The two then visited Zatanna, claiming her as the "mother". All-in-all, this is definitely one of the Joker's most bizarre adventures, but it needs to be asked if it is canon.
Is Joker's Pregnancy DC Canon?
In all likelihood, the answer is no. The Joker is an unreliable narrator at the best of times and this story is told entirely from his perspective. It's possible that what fans are reading is nothing more than a figment of his imagination, or some alternate universe playing out. Considering the inconsistencies surrounding this particular Joker though, it is likely that this is nothing more than a manifestation of his mind. The Joker's henchmen are the biggest evidence of this.
More than once, the Joker has gotten them killed in the course of these misadventures. This time around one of them was shot dead while they were hunting the Joker's child. Yet, they keep showing up in the next story, good as new and acting as if they didn't die a horribly painful death the issue before. This also rules out the multiverse theory as these backup stories follow this particular Joker, and it seems unlikely that there would be so many universes devoted to one man like this. As a result, fans have to make a reasonable guess that this is not canon and that Zatanna does not share a mud monster son with the Joker.