Warning: SPOILERS for Joker ahead.
The Joker movie completely sidestepped having its own "MARTHA!" moment and, indeed, it all but avoided Martha Wayne, the mother of Bruce Wayne. Director Todd Phillips' controversial Joker movie is a standalone unconnected to the previous DCEU movies by Zack Snyder, David Ayer, Patty Jenkins, and James Wan. But even though Joker takes place many years before Batman begins his war on crime, the grisly psychological drama is well-aware of the previous Batman movies and their tropes - including the most infamous moment from Batman v Superman: Dawn of Justice.
Zack Snyder's 2016 follow up to Man of Steel, BvS was the historic first movie clash between Batman (Ben Affleck) and Superman (Henry Cavill). Already distrustful of the Kryptonian hero's potential to be a villain, Batman plans to end Superman himself. For his part, the Man of Steel is manipulated into fighting Batman by Lex Luthor (Jesse Eisenberg), who holds his adoptive mother Martha Kent (Diane Lane) hostage. During a rainy Gotham night, a heavily armored Batman battles Superman, weakening him with Kryptonite dust, and the Dark Knight very nearly wins the fight. Just as he's about to plunge his Kryptonite spear into the alien, Superman desperately cries out his mother's name, "MARTHA!", which stops Batman in his tracks because both of their mothers are named Martha. "MARTHA!" took on a life of its own and has since been held up by BvS's detractors as a prime example of what was creatively wrong with the film. Although to be fair, some fans defend "MARTHA!" as a clever moment that acknowledges a longtime coincidence that Batman and Superman shared in DC Comics and used to the film's advantage.
Joker weaves an unexpected connection between Arthur Fleck (Joaquin Phoenix), the psychologically damaged would-be standup comic who becomes the Joker, and the Wayne family. Arthur's sick and elderly mother Penny (Frances Conroy) was the Waynes' maid 30 years ago and she is convinced that billionaire Thomas Wayne (Brett Cullin) is Arthur's biological father. Arthur goes on a quest to investigate the truth and is shattered and driven to a murderous rage by what he ultimately discovers but the film ultimately debunks that Arthur is Thomas' illegitimate son. Joker depicts the young Bruce Wayne (Dante Pereira-Olson) having a brief encounter with Arthur, Batman's future arch-enemy, at the gates of Wayne Manor and Arthur also finally confronts his "father" Thomas Wayne, who reacts violently to Arthur. However, Martha Wayne is barely in the film and this feels like a strategic choice by Joker's filmmakers.
Unlike Thomas, who is a major character and a candidate running to be Mayor of Gotham, Martha Wayne (Carrie Louise Putrello) only appears briefly in Joker but she never speaks and is never even mentioned by name. Martha's lone function in Joker is to be murdered in an alley (and have her pearl necklace broken) by a thug wearing a clown mask, which is the fourth time the Wayne murders have been depicted in a movie. Considering the numerous references to other Batman movies that Joker makes, avoiding Martha entirely is almost amusing and is possibly a response to the still-mocked "MARTHA!" moment in BvS. After all, Joker can't also be mocked for Martha if she's just a background character that the film all but brushes under the carpet.
However, unlike in Pennyworth on Epix, Martha Wayne has never been a true character in any Batman movie. She merely died, along with Thomas, in a flashback in Batman 1989. In Batman Begins, Martha is seen but never says a word while Thomas Wayne (Linus Roach) got to impart words of wisdom to young Bruce before his parents are murdered and, in BvS, Martha (Lauren Cohan) and Thomas (Jeffrey Dean Morgan) have no dialogue when the Waynes are killed in the film's prologue.
But it's because of Batman v Superman that "MARTHA!" has become infamous and now Joker made sure to avoid even saying her name. At the end of the day, since so much of Joker is disturbing and not funny - despite the presence of the standup comic-turned-murderous clown - perhaps it was wise of Joker to dodge getting any intentional laughs because of "Martha" since fans still have negative "MARTHA!" thoughts.