The Simpsons is probably amongst the rulers of this trope alongside Pokémon: The Series.
- Parodied in the episode "Behind the Laughter", where in a "documentary" about the show featuring the cast as Animated Actors, Lisa complains about how she was forced to take anti-growth hormones in order to prolong the series. Homer dismisses the idea, noting, "That's ridiculous. How could I even get all five necessary drops into her cereal? ...What?"
- The chalkboard gag for the season 12 finale, airing about 11 and a half years after the show's debut, has Bart writing "I should not be 21 by now".
- Also brought to light in other ways; in early flashback episodes, Homer and Marge attended high school in 1974; in season 19's "That 90s Show", Marge then goes on to college almost immediately — but it's now 1994...
- In "That 90s Show," Bart also lampshades this trope by saying he's "never heard" of The '90s. Hey, after all, this episode aired in 2008, and Bart is only ten... Just like he was in the first episode in 1989, and during the entire following decade while The Simpsons practically re-defined television!
- One "appearance" in a K-Zone magazine featured Lisa being interviewed: when asked what she wanted to be when she grew up, she said something along the lines of "I used to want to be a jazz musician or the President. Now I just want to be nine!"
- In one episode, Homer muses sadly about how work is keeping him away from his kids. "Bart's growing up without me. He won't be ten forever."
- One particularly bad case is "Lisa's First Word". The entire episode is basically one long joke about The '80s when Lisa was born. Nowadays she can't have been born until this millennium. Pretty much all the flashback episodes must be Canon Discontinuity to some degree.
- To give you an idea of how quickly the show retcons characters' ages, Homer is singing a hit song from 1983 in the flashback to when Marge was pregnant with Lisa. In "Homer's Barbershop Quartet" one season later, she's old enough to speak full sentences in early 1984 (the year Dexys Midnight Runners was nominated for a Grammy).
- In one episode, Gil moves into their house for the better part of a year, as demonstrated by an Exploding Calendar stopping at each holiday. Notably absent are any of the characters' birthdays, which according to this episode must all take place between Thanksgiving and Christmas.
- One episode centered around reviving the "Angry Dad" character Bart created during the late '90s Internet bubble. Those exact words were stated in the show, and no hint of an explanation whatsoever was given as to why Bart's still ten years old.
- Matt Groening once pointed out in an interview that one of best parts of doing an animated show was the kids didn't have to grow up. He cited the absurd number of times they'd done a show about Bart's tenth birthday as an example.
- Lampshaded in the Couch Gag of the episode "Them, Robot".
- This trope was spoofed in the Season 11 episode "Bart to the Future"; in a scene set 30 years in the future, the family is eating dinner together when Lisa (now President of the United States) asks where Maggie is. Marge reaches down and picks up Maggie, who still looks like a pacifier-sucking baby...and then adds "just like her mommy, Maggie, Sr."
- To sum things up, if The Simpsons had been allowed to grow up, as of now (2023) Bart would be 44 years old (born 1979), Lisa would be either 41 or 42 (born 1981)note , Homer would be 70 (born 1953, which would make him 36 in 1989, but his current age has been retconned to 40), Marge would be 68 (born 1955, which would make her 34 in 1989, but her current age has been retconned to 38), and Maggie would be 35 (born 1988). Taking the original shorts into account, they would all be two years older than the above ages. In the present day, Bart's birth year is now 2013, Lisa's 2015note , Homer's 1983, Marge's 1985, and Maggie's 2022.
- Rarely characters have ended up dying of natural causes, but this has never happened to most of the characters at the Springfield Retirement Home, such as Grampa or Jasper, despite both of them having been in World Wars previously, nor Skinner, who served in the Vietnam War in 1966.
- In the episode "Half-Decent Proposal" in season thirteen, Marge and Lisa realise with shock that Homer has gone to work on the West Springfield oil rigs. Grampa, walking in, says, "What? Homer bowled a 300 game?" (which happened in a season eleven episode called "Hello Gutter, Hello Fadder"). Marge, annoyed, tells Grampa that that happened a year and a half ago. Of course, in that year and a half, the Simpson kids haven't aged a day.
- A Robot Chicken sketch lampshades this, at least for Bart, wherein he writes repeatedly on the chalkboard "Why aren't I aging? Good God, am I a monster?".
- In the episode where Apu and Manjula's octuplets are born, Manjula goes from trying to get pregnant for a few months to being pregnant to having octuplets and for those octuplets to be older than Maggie (they're shown to be able to speak a few words while Maggie is still silent) without any of the Simpsons kids aging a day. The same thing happened when Selma adopted her Chinese baby girl.
- A 2015 Treehouse of Horror segment (specifically "Wanted: Dead Then Alive", where Sideshow Bob successfully kills Bart) hangs a massive lampshade on it, as Bob mentions that it took "24 years of trying to kill a 10-year-old child" before he finally succeeded.
- When The Simpsons premiered as shorts in April, 1987, Bart and Lisa had grown up with the Soviet Union, the Cold War and Mutually Assured Destruction. As of the most recent episodes, they have known only a post-9/11 world and by late 2010s and early 2020s, they had grown up with smartphones and Marvel Cinematic Universe movies.
- Lisa finally averts this and turns 9 in Season 32... but it is in a Treehouse of Horror episode, so this might not be canon.
- In "The Man Who Grew Too Much," Marge struggles to get through to a group of teens while volunteering at church, leading to this line as she talks to Homer about it:Marge: I just wish I could connect with those teenagers, since it seems like we'll never have any.
- Notably Averted with Mr. Burns who, despite the constant sliding timescale of the series for everyone else, is still always shown to have been a lad in the 1800s. Of course, Burns' astronomical age is a frequent gag with his character.
