With a Limited Wardrobe in many media universes, characters wear unique clothing to stand out to the audience. In the case of this character, why would they consider wearing casual clothes like everyone else when you could wear a sports jersey?
This style can be worn by passionate sports fanatics of either a popular team, or a team that they play on themselves; the Jerk Jock might sometimes wear his jersey as a Custom Uniform at school, and in some cases if a character used to play sports in school, wearing their old school jersey may be a sign that they are holding on to past glories, or that their whole identity is tied to their time as a varsity athlete.
In Japanese media, people wear sportswear-like clothing as loungewear that they nickname a "jersey", which has very negative connotations, implying that said character is lazy. It's sometimes the wearer's intention to invoke this for Obfuscating Stupidity in case they do dangerous activities, such as fighting villains.
See also School Uniforms Are the New Black, which is arguably the same type of trope, but with school uniforms instead.
- Yato, from Noragami is a God of Calamity and known for wearing the same sportswear outfit every day all the time. He insists it's cool but both his Exemplar, Yukine, and human acquaintance Hiyori call him out on it regularly, calling him lazy and gross, as if he never washes it. Possibly justified in that he does go around fighting and killing phantoms — the embodiments of human's negative thoughts, and doing other odd jobs, trying to save up for a temple of his own.
- Casey from Pokémon is a huge fan of the Electabuzz baseball team. She constantly wears the team's jersey and baseball cap.
- Ryoma from The Prince of Tennis occasionally wears his tennis club uniform outside of his training classes and matches, but he is almost never seen without his team's cap, unless he is going to school.
- Toji from Neon Genesis Evangelion is often seen in a tracksuit and jogging pants during school (the only time he doesn't is in the ninth episode). This is probably one of the reasons why he is always getting under the skin of the Class Representative Hikari (other than her infatuation with him).
- Moose Mason from Archie Comics is a multi-sport athlete for Riverdale High. However, being a Dumb Muscle character, Moose is rarely seen without a numbered jersey and track pants.
- In the G.I. Joe franchise, Bazooka stretched even the Joe's Custom Uniform policy by wearing a sports jersey instead of anything even vaguely resembling a military uniform. In the IDW comic series, when he is killed in action, the Joes hang his trademark jersey on the wall of their HQ as a mark of respect.
- Wonder Woman: In the Golden Age most of the Holliday Girls wore Holliday College jerseys near constantly, and Etta Candy in particular paired hers with shorts—rather scandalous everyday wear for a young woman in the 1940s—while the other gals wore skirts.
- In the early years of Doonesbury, B.D. (the university quarterback) played with this trope, wearing his football helmet everywhere, all the time; even instead of an army helmet while he was in the Army serving combat duty in Cambodia.
- The Monstars from Space Jam all wear basketball jerseys with the number zero. Curiously, they received these uniforms when absorbing the Liquid Assets of five NBA players, but retained the jerseys after forfeiting their powers. For the climatic basketball scenes, their uniform was different. Averted with the Looney Tunes characters, who only wore athletic wear during the Ultimate Game.
- Nobby in Grimsby wears the football/soccer jersey of his favourite Grimbsy FC (and England striker) player throughout the movie.
- Although Monty from Brewster's Millions is a baseball player, when he is due to meet with the lawyers that control his deceased relative's inheritance in their boardroom, he wears his jersey and his cap.
- Cameron wears a Gordie Howe Detroit Red Wings jersey throughout Ferris Bueller's Day Off. Considered as iconic as Ferris' patterned jacket. Alan Ruck said the reason Cameron doesn't wear a Chicago Blackhawks jersey is because Cameron's grandfather in Detroit used to take him to Red Wings games.
- Quantum Leap: In "Animal Frat" Sam leaps into a college BMOC who always wears a Chicago Bears 51 jersey (Dick Butkus).
- On The Goldbergs, Barry is seldom seen without his Philadelphia Flyers jersey, which he nicknames "Big Orange".
- On The Big Bang Theory, Leonard wears a jersey to Penny's football party to try and fit in. However, the only one he could find is a few sizes too big, and the only ones smaller were for dogs. Sheldon notes that it's more of a football gown.
- Father Dougal (page image) in Father Ted often wears a soccer jersey for pyjamas, emphasizing his characterization as an eccentric manchild.
- The members of the William McKinley High School football team in Glee are almost never seen outside of their practice and matches without the preppy varsity jackets of the team. This is probably to avoid being the targets of their own group's bullying antics, which involves throwing drinks at nerds, shoving people into lockers, or any other methods of abuse. It's notable that even though Finn and Puck are star players on the team, after joining the glee club, they slowly start to shed from the preppy jackets, until they never wear them again by the senior year (third season).
- During the DX Army phase of D-Generation X, multiple members of the group wore customized DX football jerseys. In their typically juvenile fashion, the jerseys said "Suck It" on the front and listed "69" as the number on the back.
- John Cena, a passionate sports fan and memorabilia collector in real life, wore an Unlimited Wardrobe of jerseys as part of his Doctor of Thuganomics persona. He wore a different one every week, usually according to where the show was, and in keeping with hip-hop fashion at the time, many of them were throwbacks.
- Eddie wears a #9 O'Reilly soccer jersey all the time, leading to a Running Gag of speculations about whether he's ever washed it.
- Baek Sung-Chul from God of High School is an eccentric badass genius who carries around a baseball bat, which he uses to beat up criminals or people who pick fights with him. He is solely seen wearing red athletic jerseys, even in school, which just adds to his weirdness.
- Kevin from Daria wears his football uniform all the time, even outside of football practice.
- The titular group superheroines in Groove Squad are only seen in three outfits throughout the entire movie: their cheerleading uniforms, their supersuits in the superhero-forms and the dresses they wear to their High-School Dance at the end of the movie.
- Kevin Smith is often seen wearing a hockey jersey. Sometimes it's an actual Red Devils jersey; other times it shares the same color scheme and layout, but has a different logo.