The animators at Warner Bros. Animation pulled no punches. The "Laughing Bat" isn't just Batman telling a joke; he is physically distorted:
During the golden age of internet horror stories, a user on the Creepypasta Wiki wrote a fake "lost episode" entry for The Batman titled "Laughing Bat." The story claimed that the episode aired exactly once at 3:00 AM in 2006. In the fake plot, Batman kills the Joker, but the Joker’s spirit infects the Bat-computer. Every screen in the Batcave shows a smiling bat. Bruce Wayne goes insane and starts laughing while putting on the cowl. the batman 2004 laughing bat
The story included a "screenshot" (actually a fan-edited image of the bat-logo with teeth). The myth stuck. To this day, many fans searching for "the batman 2004 laughing bat" are looking for this lost episode. It does not exist. The animators at Warner Bros
The "Laughing Bat" or more commonly referred to as "The Joker's Playing Card" or simply "Laughing Gas" plot device from Christopher Nolan's 2008 film "The Dark Knight" (not 2004) where the Joker uses a toxin that induces a paralyzing fear and a comically exaggerated, uncontrollable laughter in those affected, shares some thematic elements and visuals with the concept you might be referring to. However, focusing on a supposed 2004 film related to Batman and a laughing bat: In the fake plot, Batman kills the Joker,
In a modern landscape saturated with "evil superheroes" (Homelander, Omniman, The Batman Who Laughs), the 2004 Laughing Bat remains effective because of its brevity and intimacy. It isn't a multiversal apocalypse. It is one man, in a machine, fighting the ghost of a clown.
The Batman 2004 Laughing Bat serves as a thesis statement for the entire series: that Batman’s greatest superpower isn't his money or his gadgets—it is his unbreakable will. To laugh is human; to refuse the joke is divine.