Bowling is apparently a huge deal in Bowling King. No, seriously. Professional bowlers are all either incredibly badass or Bishōnen prettyboys. Oh, and then there's how main character Shautieh Ley's ultimate goal seems to involve taking over the world with bowling somehow; while this isn't explicitly stated, chapter opening pages tend to feature things like a Rushmore Refacement where all of the faces are Shautieh (and similar ones with the Sphinx, etc.) and Shautieh disrupting other sports events.
DC Comics had a Golden Age hero called Manhunter, then bought another Golden Age hero called Manhunter. In a Retcon, the two men had an argument over who got to keep the name, and they settled it by having one of them go to another universe. This a Lampshade Hanging on how writers in comics loved to remove problems by having them turn out to take place in alternate universes.
"You don't understand man." "He TOUCHED my dice!"note Ask any hardcore gamer in Real Life. Touching someone else's dice/mini/whatever without permission can be considered a breach of etiquette, and with some players, is indeed Serious Business.
In one Calvin and Hobbes strip, Calvin throws an enormous hissy fit after losing a game of checkers to Hobbes, culminating in him passing out in exhaustion. When Hobbes points out that it's just a game, Calvin cheerfully replies: "I know! You should see how I act when I lose in real life!"
Chewing gum is Serious Business in the Calvin and Hobbes universe. Calvin is an enthusiastic reader of a magazine called "Chewing" which is dedicated to it, and informs an incredulous Hobbes that as many as twelve such publications exist.
An early strip had Lucy repeatedly shouting "OLLIE-OLLIE-OXEN-FREE!" Violet came by and pointedly told her that the expression was "Ollie-Ollie-All-are-out-in-free." This left Lucy more thoroughly humiliated than she'd ever been in her life.
Once, when Lucy caught Linus about to throw a snowball at her, she angrily demanded that he take that very snowball apart snowflake by snowflake. ("No pieces! No chunks! One snowflake at a time!") Poor Linus was out in the snow until nightfall.
Linus and his blanket. When he had to go without it for a couple of weeks, he fainted several times...in a single day.
Linus also had a pretty intense crush on his teacher, Ms. Othmar. When she was fired for going on strike, he threw an enormous tantrum and vowed to turn the whole matter into a federal case. He also snottily told his substitute teacher that, sure, he'd learn the lessons the way she taught them, but she still wasn't Ms. Othmar.
Schroeder. How dare you mock Beethoven in his presence!
Bookhunter takes place in an alternate-universe 1970s where books and libraries are so important that a branch of the police is devoted to investigating library-related crime.
Agent Bay: In many respects the American Library has become the most basic First Amendment institution. We are guards, yet we guard no less than the sum of human knowledge. We are the library police.
The Far Side once had a Showdown at High Noon having ended in defeat for the older cowboy, treating it with all the gravity you'd expect... except it was at ping-pong.
Older gunslinger: Well, you won. Now every player in the world will come after you, looking to make a name for himself... Welcome to Hell, kid.
This comic was based on one of Scott Adams' coworkers, who actually said "I will fight you to the end of the earth!" To him, it was serious business.
In Welcome to Tranquility Captain Cobra and Mongoose Man are not just enemies, but "enemies to the DEATH." Unfortunately, their advancing years are actually bringing them pretty close to that goal line and they have both retired from super-activities, heroic and villainous alike. So, what is left for them to be enemies over? Why, the apple tree that looms over both their properties, and who has proper ownership over the apples that fall down on either side of their fence. Just ask Sheriff Lindo, apples are serious business.
Beef is Serious Business in the Crapsack World of Give Me Liberty. Fast-food restaurants wage wars for farmland, people commit suicide for hamburgers, and there's even a 94th Amendment outlawing red meat.
The people of a Hannoverian village who want to celebrate the birthday of their ex-king (Hannover was conquered by Prussia in 1866; some people nursed a grudge because of this, and pro-Prussian Wilhelm Busch wrote this story as a Take That).
Pinkie Pie: Luckily, I always travel with an "I'm sorry" cake! I also have "I am sorry" goodie bags! Twilight Sparkle: Uh, Pinkie, I don't think we have time for cake... we are only an hour away from the Changeling kingdom... Pinkie Pie:EAT... THE... CAKE.
When Wonder Woman was stuck working at Taco Whiz, she took the job very seriously. Then again, she takes everything seriously, except Batman's brooding.
According to the Batman: The Animated Series "Mad Love" comic, The Joker takes comedy very seriously. Only he gets to tell jokes during his crimes; he throws a tantrum if anyone else makes a crack. And if people don't understand one of his gags and he has to tell them why it is funny, that takes all the fun out of it - even if it involves killing Batman.
Joker[angrily, to Harley Quinn]: My jokes are elegant in their simplicity. You see them, you get them, you laugh - end of joke! You should have remembered when I told you that a long time ago; it's one of the few real truths of comedy!...You're always taking shots from folks who just don't get the joke!note Admittedly, this is a very sensitive Ironic Echo for the Joker because it was, verbatim, what he had told Harley earlier after relating to her the story of his father breaking his nose and putting him in the hospital when he was a boy because he was angered by a prank the young Joker tried to play on him - but then again, Batman points out that the story is most likely a lie. [strikes Harley repeatedly with a large fish, sending her crashing through a high window and down to the street far below, nearly killing her]
There's also the Adventures of Batman & Robin (a Saturday morning spinoff show of the above) episode "Make 'Em Laugh." The Joker is outraged because a panel of three comedians won't give him the annual trophy for best comic in Gotham City (despite the fact that he wasn't even eligible to compete because registration had already ended), so he 1) steals the Mad Hatter's mind-control microchips at Arkham and puts the Hatter himself in a microchip-induced coma from which he might never wake up; 2) kidnaps and brainwashes the three comedian-judges, turning them into super-criminals and indirectly getting one of them sent to the hospital with life-threatening injuries; and 3) replaces the judges with three of his own men, forces the emcee to introduce him as the only contestant, and terrifies the audience by juggling grenades until Batman and Robin show up. Batman scolds him for ruining so many people's lives just because he couldn't get a cheap trophy.