Akeelah and the Bee has a character named Dylan, whose father insists that he be Asian and Nerdy and beat the titular character in the national spelling bee by saying that if he comes in second place in anything, he'll be second place for life.
Another Disney Channel example would be Alley Cats Strike. however, despite first guess, the Serious Business isn't so much bowling itself, but rather the rivalry between the city's two schools. Though in this case the True Companions are as bewildered by their schools behavior as anyone else would be.
American Psycho does this with a number of yuppy affectations, but most especially business cards. There's a serious rivalry in Patrick's firm about how good they look, right down to the subtle shades of white and the font. In fact, they're so serious, Patrick kills the people who have business cards better than him. Or doesn't he??
In Avalon, the eponymous game is so serious Ash makes a living out of playing it.
Balls of Fury does it with Ping-Pong table tennis... In a ludicrously over-the-top way.
In Band Slam, band competitions are "Texas high school football big."
The sport BASEketball from the film of the same name becomes serious business to many people very quickly, becoming one of the most popular sports in America only a few years after being invented by two drunk guys. And then the plot of the film is based around one of the team owners trying to make it Serious Business, trying to get the rules changed so making serious money is more possible.
Walter in The Big Lebowski has bowling. He's willing to pull a gun over a rules infraction, and he'll even break the Sabbath to prevent a team member from quitting.
In the Bill & Ted movies, the music of Wyld Stallyns has become the basis for the entire society of the future, curing diseases, fostering world peace, and improving people's bowling and minigolf scores.
Mildly averted in Blackball. The film itself is a spoof in which bowling is a very serious business. When the hero sets up a rivalry with the (60 year old) reigning champion and falls in love with his daughter, he wants to show her some of the magic and importance of bowling. Her response: 'I HATE bowling'. He more or less accepts this.
Blackballed: The Bobby Dukes Story does this with professional paintball.
In the DCOM movie Camp Rock 2 there's a song called "Don't back down," which makes a rivalry between summer-camps out to be incredibly serious business. It's hilarious until you realize it's not meant as a parody.
Celtic Pride is about a couple of Celtics fans who kidnap the Utah Jazz star player so their team can win. In the end, all three men learn to just enjoy the game. That is until football season...
A Christmas Story: Told from the perspective of a child, everything is serious business. When Schwartz issues a "double dog dare," then skips the "triple dare" to go straight to the "triple dog dare," the crowd of boys are suitably impressed by the gravity of the situation. In another vignette, Ralphie decodes Annie's secret message like it's a matter of national security.
In Crossroads, blues music is apparently serious enough to sell your soul to the devil for, and motivation enough to break self-confessed murderers out of custody. The selling your soul is a Shout-Out to blues legend Robert Johnson who claimed to have sold his soul to the devil at the crossroads to play guitar so well.
The Disney Channel move Dadnapped is all about this trope, in which the main character's father is kidnapped by his fans.
Duplicity plays this straight with the main plot; competition between two cosmetics companies is treated as Serious Business. Competition in the microwave pizza industry is dismissed as silly.
In E Xisten Z, people are willing to commit murder over the titular video game. This was partly inspired by the trials and tribulations of the director's friend, Salman Rushdie. A major theme of the film is just how fanatically people can react to works of art.
In The FP is built around the inherent comedy of the gangs of Frazier Park dueling by playing "Beat Beat Revelation." For some reason this is abandoned in the final act, when a duel escalates into standard gunfights and fisticuffs.
Furry Vengeance would have the animals tormenting Brendan Fraser's character because they aren't going to take well of his plans of tearing down their forest for a development.
God of Cookery is a film about a disgraced chef battling to regain his honour.
The crowd is really unnaturally engaged during all of the debates in The Great Debaters, to the point that it's kind of distracting.
In Green Street (or Green Street Hooligans for Americans), a visiting American learns that association football appreciation is Serious Business in the UK, falling into a circle where it leads to brutal gang brawls, mutilation, and outright murder.
Planet Terror: JT, the steakhouse owner, has a falling out with his brother, the sheriff, over his barbeque sauce recipe. Whenever they talk on the phone, the conversation turns to the barbeque sauce in under a minute. After they've both been shot, JT finally tells his brother the recipe, and the sheriff uses his dying breath to promise never to tell anybody the recipe.
The movie Hatley High, in which chess is very serious business
The zombie film Hide And Creep has a precious moment of this toward the beginning, where one of the main characters enters a diner and orders Coke, only to find out that they only serve Pepsi. He then goes into a massive pro-Coke/anti-Pepsi rant, finally summing up that the diner was "like red China" for not giving the diners their choice of cola.
In High School Musical, basketball is serious business. As is drama, at least in the mind of its teacher, if not in anyone else's.
In Hot Fuzz, everyone's obsessed with Sandford winning the Village of the Year contest, taking it to homicidal extremes.
In a World...: Voice-over work, specifically for movie trailers, which is treated as far more prestigious than other jobs that use the same skill set like advertising for products other than movies, voice coaching, narrating audiobooks, or voice acting for animation.
In Kill Bill, Hattori Hanzo invokes this trope by name while discussing Japanese pronunciation with the Bride.
The King of Kong is about all the drama behind Donkey Kong world records. "Donkey Kong kill screen coming up..." There was even more serious business behind the scenes. Careful editing played up the rivalry and made a less obvious villain out of one of the players.
Bowling seems to be pretty popular for this trope, as Kingpin also did it, what with Bill Murray's character getting his young, upstart rival's hand shoved into a ball return through a "misunderstanding" with some gangsters... who also bowl.
In The Last Starfighter the entire trailer-park drops what they're doing runs over when they hear Alex is about to break the record score on the Starfighter video game. They are all elated when he does, and Alex later tells his mother that this day will be remembered forever in the trailer-park. Possibly justified, as there doesn't seem to be much else to do there, and it's implied they have all played it at some point.
In Mash, the priest lets the main character know that one of the others is severely depressed and considering suicide by stating "He said poker is only a game"
In Mean Machine and The Longest Yard, association football and American football are Serious Business to convicted felons. However, their primary motivation is actually to hurt the guards on the opposing team as much as possible.
The Mighty Ducks: The local newspaper not only covers the games of a bunch of 12-year olds, but features them with headlines, one including a dramatic "Face-Off" of the two coaches before the final game. The villain coach tells his team to intentionally hurt a player on the Duck's team due to him being on the Duck's due to re-zoning. Jesus Christ man, it's a game between 12 year olds!
D Grade suburban cricket is this to Teddy and Colin in Save Your Legs. To the rest of the team, not so much.
Jack Black's character puts it in exactly these terms in School of Rock: "Now, this is serious business here. We've got a mission. Putting on a great rock show is the most important thing. One great rock show can change the world."
Speed Racer has automobile racing, which has become by far the biggest global sport and has a major impact on the prices of the biggest corporations.
Hip hop street dancing is Serious Business in Step Up 2: the Streets. This is cemented from the very beginning with a ridiculously dramatic opening monologue. It gets worse within the first 5 minutes, where a subway prank involving dancing is reported on the news as though it was a terrorist attack! (right down to the subway being closed down)
In Tampopo, most of the characters treat the preparation, serving and consumption of food as serious business.
Even narrower that than. Not simply food, but noodle soup!
The Ten does this in most of its stories. Most of the plots are motivated by people obsessing over fairly ludicrous things. It might just be a statement on people taking religion overboard, but it gets pretty inane. For instance, certain segments hinge entirely on people obsessing over:
A man half-buried in the ground after a skydiving accident.
In A Very Harold & Kumar 3D Christmas, Harold's father-in-law (played by Danny Trejo) takes Christmas and especially Christmas trees very seriously. Naturally the tree he brought is destroyed by Kumar and the title characters have to go out and find a replacement.
Wallace & Gromit: The Curse of the Were-Rabbit is what the writers call "perhaps the first vegetarian horror movie." To keep some kind of tension, given that the monster is no threat to people, it turns out that everyone in town is insanely protective of their vegetables. For them, country fairs are serious business. "We're simple folk! It's all we have!" NB: In real life, competitive growing is sometimes taken quite seriously, and incidents of sabotage and theft are not unknown.
Gently parodied and lampshaded in Whip It; the protagonist thinks rollerderby is a huge deal, but it's mostly because she lives in a small town that she hates and has nothing else going well for her. Her team's coach is obsessed with winning, but the rest of the skaters have a more relaxed view, and when they lose the final, they still celebrate because hey! They made it from last place to the final!
Played first for comedy and then for horror in The Wild Hunt, in which a group of LARPers take the game far too seriously.
The Wizard plays with this trope in that in the world of the film, Nintendo is an integral part of the culture. Everyone knows it, everyone plays, and everyone's plugged in, to the point where "Video Armageddon" is greater than the Super Bowl.
Sometimes futuristic films will be set in a world where a bizarre game has replaced war:
In the original Rollerball, wars have been replaced by a brutal form of roller derby.
In Robot Jox, America and the USSR resolve land disputes not by nuclear war, but by gladiatorial combat between giant robots. The trope is almost inverted in the fact that the bouts are televised and treated like sporting events by ordinary citizens.