Kearney Zzyzwicz is one of the infamous gang of bullies in The Simpsons, but since he has a child of his own, how old is he really? Students at Springfield Elementary can guarantee 3 things: a dinner that tastes of old gym mats, a sub-standard education, and their lunch money stolen. Responsible for the latter are Jimbo, Dolph, Nelson and Kearney, who prowl the schoolyard on the lookout for nerds, dweebs and losers with jangling pockets. But while Jimbo and Dolph appear to be in their late teens and Nelson is part of Bart Simpson's class, it's heavily implied that Kearney is much older - a fully-grown adult repeatedly kept behind due to academic failure.
Voiced by Nancy Cartwright, Kearney is one The Simpsons' many colorful recurring characters, and like many other supporting figures, his age is kept deliberately vague. Since none of the characters actually get any older, pinning down ages in The Simpsons is inherently a tricky business, but in the case of Kearney, there are a few real-world references that help clarify how much older this gruff single parent is compared to his classmates.
As seen in "A Milhouse Divided," Kearney has a son of his own and is already divorced, despite still being in school. Kearney Jr. is around 7 years old, but might possibly have two brothers. A younger (albeit strangely muscular) toddler plays with Maggie in season 20, and then Kearney himself makes a reference to having a teenage child. Season 7's "Lisa The Iconoclast" provides some salient details on Kearney's age. The bully claims to remember the U.S. Bicentennial (1976) and is seen shaving while sitting with his fresher-faced classmates. With this episode airing in 1996, celebrating the Bicentennial would make Kearney at least 20 years old. However, the same episode also sees Kearney drop the line "those tall ships really raised folks' spirits after Watergate." If Kearney was alive during the Watergate scandal, which began in 1972, this adds an extra couple of years, making him 22/23.
23 years-old feels like a reasonable estimate for Kearney. He'd be old enough to have young children and shave, but might still look young enough so as to not physically stand out from his classmates. However, there is evidence to suggest Kearney's true date of birth could be even earlier. Otto, the Springfield Elementary bus driver, claims to have been in the same 3rd grade class as Kearney, and the permanently-stoned Walkman addict was born in 1963, making Kearney at least 33 years-old, depending on whether or not he had already been held back a few grades. 33 years-old might make more sense, as it would explain Kearney's line about having a teenage child. Kearney would also be more likely to remember the Bicentennial and Watergate if he was school age, rather than a newborn.
Like many elements of The Simpsons, Kearney's age is subject to change depending on what each story or gag calls for at any given time. Making Kearney out to be an adult gives The Simpsons plenty of comic material ("I sleep in a draw"), but the references don't stop him being a regular child when the joke calls for it - using a fake I.D. to buy alcohol from Apu's store, or saying he's a "teenager and a parent of a teenager," for example. This is a common trope on The Simpsons, and one that can be seen with the age of other characters such as Mr. Burns and Ned Flanders, whose years constantly fluctuate for comic effect.