Unsportsmanlike Gloating

"Yes! We have defeated you for all time! You will never rise from the ashes of your shame and humiliation!" Beat "Well, that was fun."

—Azula after a game of volleyball, Avatar: The Last Airbender

In short, being a big gloat when winning in a situation where it's considered just rude, and unsportsmanlike (even if it doesn't involve sports).

Whether it's being subtly rude about it, or outright shouting "Loser! Loser! Nya, nya NYA!", this trope shows the winner is just being a Jerkass about it.

Often seen when The Rival is a Smug Snake.

Note that this is not just wanting to crush your enemies and hear the lamentations of their women. This is strictly for when you win and are being a jerk about it. Although doing those things just after you win does count.

Compare Evil Gloating, Cherry Tapping, Second Place Is for Losers, Taunt Button.

Contrast Graceful Loser.

No real life examples, please; we already know how many jerks there are in the world.

Examples of Unsportsmanlike Gloating include:

Anime and Manga

Full Metal Panic!
- During Fumoffu, there's the rugby team that Sousuke coached. After their overwhelming victory, they are shown mocking the fallen team horribly. (To be fair, the losing team had belittled Sousuke's team earlier in the story... but that doesn't make it right.)
- Sousuke himself is shown to do this a lot after winning fights. He loves informing his fallen enemies exactly why they're such losers and failures. (In his defense, at least one case was due to his misunderstanding the enemy's lamentations of why he lost for a wholehearted request for advice, and decided to inform him literally why he's such a loser.)
Pokémon had a fairly recent^[when?] example of this, courtesy of everyone's favorite Jerkass, Paul/Shinji. In the first of what would be his many dick moves, right after he battled Veilstone Gym Leader Maylene, took out her team with ease and received his Cobble Badge, Paul gave a glowing critique on her skill as a Gym Leader:

"You're the weakest. The weakest leader I ever fought, and this lightweight Badge is just like you."

Iron Wok Jan: At one point Jan follows a defeated opponent out to the street to taunt him some more as the fellow looked insufficiently crushed.
In Azumanga Daioh Yukari does this after the first two of the three Sports Fest, the second one complete with the Finger Point and "Loser Team Loser Team" (her class just walks away when she starts it).
In Fairy Tail, Flare Corona mocks Lucy mercilessly after she wins their match in the magic tournament. Even worse than usual since the only reason Flare won was because one of her teammates interfered from the sidelines to depower Lucy right when she had Flare on the ropes. Flare doesn't get off completely scot-free, though — in a later chapter, one of her other teammates beats her up for being so weak.

Film

Big Fat Liar has an over-the-top example with Marty Wolf when he almost wins:

Yeah, I stole your story, whoop-de-doodle-do! I STOLE JASON SHEPARD'S STORY AND TURNED IT INTO BIG FAT LIAR! Do you know who's listening? Nobody and get used to it. Because I will never-ever-never-ever-ever-ever-ever-infinity tell the truth!

- Ironically, this backfires instantly after he finishes.
Invoked on Chicken Little:

Announcer: This excitement isn't just about the fun of baseball. It's not about the prize. It's about the gloating, the rubbing their noses in it, the nah-nah-nah-nah-nah-we-beat-you taunting, if you will, that comes with the winning.

Good Will Hunting has Will do this as an awesome moment after getting Skylar's number, as the guy he beat is a bit of a jerk. Has led to an Ascended Meme:

Will:: How do you like them apples?

Cars: Chick Hicks, after winning the Piston Cup by blatantly causing an accident for the car who'd been beating him for years. If the dirty race hadn't cost him the Dinoco sponsorship already, then the gloating certainly put him over the top.

Literature

A Berenstain Bears book dealing with being a bad winner.
Discworld: Esme Weatherwax insists on not killing her opponents since it's no real victory if you can't rub it in their faces. It's a witch thing. As demonstrated by Greebo, it's also a cat thing.

Live-Action TV

In Perfect Strangers, Larry talked about how Mr. Gorply would rub the bowling trophies he won in Larry's face. Balky tells Larry to be a good sport when he finally wins, but then agrees to let Larry have one phone call about it.
In Sabrina the Teenage Witch, her cousin chanted "I won! I won!" whenever she won some board game or card game.
The King of Queens: Arthur Spooner has been shown to be much like this, which had—strong effects on his daughter.
Hot Shot: In this Chinese drama series, one of the more famous and well known scenes from the series consists of a music video-like part where the main characters taunt the opposing basketball team after their win. They're shown to dance their own choreographed victory taunting dance to Nese's "Superman" (which, in and of itself, is pretty much a song dedicated to Unsportsmanlike Gloating).
Top Gear
- Jeremy Clarkson is quite prone to this, the Large Ham-y fellow.
- His co-presenter Richard Hammond can be just as bad. A particularly egregious example appears in the Top Gear vs. D Motor crossover challenge.
Regina is prone to this on The Steve Harvey Show and always says, "BAM! In your FACE!" whenever she wins something, no matter how big or small, and especially if it's against Steve.
In the Colbert Report, Stephen Colbert calls John Stewart to gloat [1] that he won Emmys, ending John's 10 year winning streak. John Stewart isn't upset in the slightest.

Video Games

World of Warcraft allows and even encourages players to use emotes such as /laugh, /pity and /hug on the bodies of their recently-deceased enemies. The Forsaken can even eat the corpse. Corpsecamping the opponent can be considered a more extreme version of this, making sure that the enemy stays down. You can also teabag dead enemies, as mentioned below.
Many video games, primarily FPS games, have this in the form of "teabagging". Someone scores a kill on you and they celebrate by going to your corpse and repeatedly squatting down on your face. It isn't enough that they killed you, they also have to violate you as well. Hilarity Ensues if the teabagger gets killed while not paying attention and gets teabagged himself.
- The stupidity of this behavior was lampshaded in this Penny Arcade strip.
Sonic the Hedgehog games have the titular protagonist get up to this. For example, in Sonic Colors:

Sonic: (gloating over a defeated boss) Wow, sometimes I even impress myself! For a second there I wasn't sure I was going to pull it off... Oh, who am I kidding, we both knew how this would end.
Tails: Uh, are you talking to the broken robot who can't hear you?
Sonic: ...Maybe. That's between me and the robot.

Most Fighting Game characters - including - Street Fighter, Guilty Gear, and World Heroes - do this to some degree the winner of the match using their victory quote to gloat over their fallen and often visibly injured opponent.
- Fighting games with a Taunt Button do not permit taunting after a round is finished to avert this behavior in-game. The Guilty Gear series is one of many Notable exceptions - taunting the opponent when a round is over will instead give them a full Super Meter for the next round.

Web Comics

Original Life: Here, over volleyball.
The Bronze Medal comic and its meme derivatives feature a guy being awarded a bronze medal, making an ass of himself of gloating and then being revealed to have gotten 3rd place.

Western Animation

Azula in the Beach Episode of Avatar: The Last Airbender.
The Simpsons: Marge Simpson spoke on this subject after Bart won a soapbox car race.
- In that same episode, both Bart and Homer dabble in this after Bart won the big race, and even after Nelson was decidedly gracious in defeat.
South Park:
- Cartman embodies this trope. In fact, Kyle got him once by deciding not to be annoyed he lost, and Cartman was furious.
- That jerk professional skier who challenged Stan to a ski race in the episode "Asspen", despite being many years older than Stan and being super-experienced (whereas Stan was just learning). Stan knew he was going to lose, he acknowledged that he'd lose, and he participated only so the other guy would leave him alone after he lost. That didn't stop the other guy from rubbing it in Stan's face. Of course this was a parody of underdog sports movies.
- And in addition to that, there's also Randy Marsh during the Pinewood Derby. He pretty much gloats and mocks the rival's father, who later suicides.
- From "Scott Tenorman Must Die":

Cartman: "Yes! Yesss!! Oh, let me taste your tears, Scott! Mm, your tears are so yummy and sweet."

The SpongeBob SquarePants episode "Skill Crane" had Squidward becoming obsessed with winning a prize from a crane machine to the point of using the deed to his house. However, once he gets one after several hundred dollars' worth of quarters, he becomes absolutely insufferable to everyone, even taunting a child who had just failed one attempt.

I'm a winner, see my prize! You're a loser who sits and cries!

In the 2003 Teenage Mutant Ninja Turtles cartoon, Michelangelo will often do this after beating his brothers at something.
Mertle from Lilo & Stitch: The Series just loves to do this after she wins.
King of the Hill
- Hank's old high school rivals won the state championship decades ago due to Hank breaking his ankle, and every day on the anniversary of their win, find every member of the old team (Hank especially) and gloat. To the point of barging into their home while eating dinner. Decades later. In order to put an end to it, Hank gets the team back together and challenges the other team to a rematch; they end up winning, and a year later they're rubbing it in the other team's faces.
- Another episode has Bobby and Peggy betting on mundane things. What are they betting on? Bragging rights, specifically the kind that let you act like a total jerk. Later they move to reverse bragging rights, meaning you need to shower the winner with praise.
In one episode of Arthur, D.W. beats her brother at checkers and starts singing and dancing about "I was checker champ, and Arthur checker chump!"—for an entire year.