In Tales of Graces, the team is discussing ways to enter the Big Bad's impenetrable dome whe... Hey what's Pascal doing with that hunk of metal and the computer?
Divinity II: Ego Draconis has a permanent Undead minion which is already quite wacky. However, whenever a cut-scene triggers it will keep doing its random thing. So there can be an evil boss gloating about how you walked into his trap and you are at his mercy and foolish... while your Undead pet is pissing on his leg.
In Bad Company, there are a few first-person cutscenes where Sarge talks to Juliet about their next objective, while Sweetwater and Haggard play Rock, Paper, Scissors behind him.
As well as Haggard tickling Sweetwater like a bug, and Sweetwater showing Haggard golf swing techniques.
Minor case in Resident Evil 3, but a lot of fans thought it was absolutely hilarious that there is a shop vacuum and random mundane cleaning supplies in the background beside the weapons locker that contains an M66 Rocket Launcher in the basement of the Dead Factory. Can you imagine explaining that to the new janitor?
Umbrella Scientist: Hey Frank! Go get the shop vac! Yeah, it's in the basement beside the rocket launcher!
In Resident Evil 4, while Ashley and Luis are having an argument, Leon is running around and barricading the doors in the background.
This type of thing occasionally occurred in Paper Mario: The Thousand-Year Door, with characters having smaller text bubbles in the background. At the beginning of the game when Mario is talking to Goombella in Rogueport Plaza, a couple of grunts from the Pianta syndicate can be seen in the back roughing up a couple of Robbos. The game to come is rife with yet more shenanigans such as this; sometimes they stop being background events to intrude upon business at hand (such as the audience during the fights clowning around, only for a Shy Guy to flip its lid, leap onstage, then rush off in a panic).
The same game also had a moment that doubles as a Meaningful Background Event. When you're searching for General White all over the game's main locations, you return to Fahr Outpost to tell the mayor that you couldn't find General White anywhere...cue General White coming out of a house on the background asking to himself where could the mustached-man be, before returning to his house, while Mario is talking to the mayor, both completely oblivious to General White being a few steps close.
Although not as much and usually not with text bubbles, the first game also had some moments here and there where townsfolk will be seen talking to each other or doing other little events (such as when Rowf first builds his badge shop with his son, which caused a few of the pillars to fall and both having to repeatedly put them back up). Too bad they tend not to last long after each new story event is completed.
Luigi tends to do this in the Mario & Luigi series regularly. During the opening sequence of Bowser's Inside Story, for instance, Mario and Luigi are in a meeting with Peach and the Toads. Throughout the meeting, Luigi slowly falls asleep on the table and somehow manages to sleep through Bowser interrupting the meeting, destroying a section of said table and nearly setting fire to the princess, leaving Mario to fight Bowser on his own. Throughout the battle, you can see Luigi, still fast asleep. Bowser attacking the castle has to get boring after the third time or so.
When you finish a race in Track Mania, the camera stays at the finish line while your scores are displayed. Many tracks position the finish such that behind your scores, your car is sent flying into a pool, wall, or off into the air. Hilariously.
The same thing happens at the end of matches in Battlefield 2. The now-pilotless planes become indestructible and often come careening into view in hilarious ways.
Need for Speed: Shift has drift races, where the car becomes notoriously difficult to control. After finishing the race the computer will take control of your car in an attempt to get it driving around the track looking cool. Except for wide-open drift course finish lines (which are pretty rare), the computer will inevitably lose control of the car and smash into...well, anything nearby, really. While your score is displayed.
In thisLet's Play of Red Faction Guerilla, at the end of a mission, an enemy vehicle unscriptedly knocks a character off screen... a character that, as mentioned in the beginning of the video is never seen again in the game.
Daerun: Yeah, I don't think we're going to be seeing Carmen again.
It's hard to concentrate on important Yuna-centric scenes in Final Fantasy X when Tidus and Wakka are fooling about and attacking each other in the background.
Just after Tidus learns the Jecht Shot, when talking to Yuna, you can see one of the blitzers try to imitate the move and fall on his ass.
This is his default animation for the rest of the night, until you go to sleep. It's awesome.
In Final Fantasy XII there is an early scene in which Larsa walks up to Penelo, who was caught after being set free by her kidnappers. The party is hiding behind some structures in the scenery. Once Penelo is show, Vaan walks out into the open to go after her...only for Balthier to grab him by the arm and drag him back before anyone sees.
This happens a lot in Breath of Fire III. During one conversation between Momo and Palet at the Plant, for example, Nina and Ryu can be seen having a spat, which ends with Nina sticking her tongue out and Ryu crying.
A regular occurrence in Shadow Hearts. They're usually Yuri's fault, helping to establish how he doesn't give a crap.
A notable one is after rescuing Anastasia, while everyone asked what she's doing - Yuri is shown dancing with the wolf.
Even during From the New World, these are commonplace. One occurs when stoicTsundere Shania returns to her native village in the Grand Canyon. While she's discussing a matter of great importance with her bodyguard Natan in the foreground, protagonist Johnny and the rest of the crew - which by this point includes a Polish immigrant McNinja, a giant talking cat and an Antonio Banderas Expy - stand around watching and acting like complete morons.
There are humorous off-camera hijinks throughout Ratchet & Clank. In one of the infobots in the first game, an anchorwoman (anchorbot?) covers news stories involving a blob monster infestation as an exterminator get eaten by one of said creatures shortly after waving to the camera. The monster later devours the reporter, ironically after her stating that she was completely safe from the blobs.
In A Crack in Time, Quark makes a very dramatic speech about how life is precious and how it would be wrong to kill the War Grok. Meanwhile, Ratchet is in the background, desperately trying to keep said War Grok from eating him.
In Mother 3, during a tragic scene with Fuel and Lighter, a bird can be seen apparently humping a flower if you start the cutscene at the right time.
Melee, Great Bay: The moon slowly falls toward Termina. At the last second, giants push it back into the sky.
Melee, Mute City: It's very possible for the F-Zero machines to get totaled.
Many stages: Random characters flying through the background.
Metal Slug is rife with these. The first stage in Metal Slug 2/X has a businessman and a local attempting to negotiate. Later in the stage, upon blowing up a truck, a human baby happily crawls around the area, as if nothing is happening. In Stage 3, several mooks on the ground below the train can be seen engaging in random acts such as having funny conversations and sunbathing.
The businessman's backstory is that he is a video game salesperson for the company that makes Metal Slug, and has a chronic habit of losing the briefcase full of merchandise he's trying to sell to his customers, and blaming the briefcase's disappearance on the client stealing it. He yells at a young boy for this reason on one level. It's you who takes the briefcase for points, naturally, and if you stick around you can see the businessman realize his briefcase isn't there anymore and flip out on the client.
Melty Blood has this twice with Neco Arc Chaos's midboss stage where the Damien Corps are having a party of some sort in the background and Satsuki is peeking in from even farther behind that.
Open sandbox games such as Grand Theft Auto: San Andreas. While busy doing your own missions, it's possible to pass cops in a gun fight (sometimes with each other) or see a two seater plane just slam into a record building. Just two of many examples.
This also happens in Just Cause 2, with the rebel factions occasionally getting into fights with military and then driving off in random vehicles. Planes frequently crash into skyscrapers in Panau City, too.
In Bully, you can sometimes see people randomly start a fight or walk up and pull the fire alarm in the school.
Some of Eggman's best in Sonic Colors is the commentary he spouts in the background, spending much of the game parodying the intercom announcements at theme parks.
Would the owner of a white hovercar shaped like an egg please report to the front desk? Your car has been broken into. Repeat. Would the owner of a white hovercar shaped like an egg please report the front desk? Your car has been broken ió wait a minute, what the heck?!...
This ride not intended for small children... Or big babies!
Visit the Bucket'O'Sushi... Now with FISH!
Anytime in Sonic Unleashed where Chip is not in the foreground. Activities range from doing the backstroke in mid-air to stealing a teapot in Professor Pickle's lab.
Team Fortress 2 regularly employs the trope within its "Meet the Team" videos.
In "Meet the Medic" the x-rays attached to a light box in the back of the operating room reveal that the Heavy has had a bomb lodged inside him. The extracted bomb is in the bucket underneath the x-rays.
You can also peer through the areas that are barred from your access on other maps, revealing gems such as...
The panel from "Meet the Spy" at Doublecross—it even lights up when the intelligence is stolen.
Several BLU NPCs are standing in front of a black board behind Stage 1 of Thunder Mountain, and they randomly taunt from time to time.
The RED Team has a swimming pool on Stage 2 of Thunder Mountain, and NPCs can be seen lounging there.
A RED Sniper can be seen camping on Stage 3 of Thunder Mountain.
Humorously-appropriate signs also appear in the "Meet the Team" videos, such as a Soldier conking out the constantly-cigarette-toting Spy with his shovel while a "No Smoking" poster is in the background in "Meet the Soldier".
The "Meet the Team"'s title cards say "COPYRIGHT LOLOLOL" instead of an expected actual copyright notice.
Bug! - At the level endpoint of Quaria Scene 1, you'll see a scuba-diving bug chasing a small fish offscreen, wait a while, and he comes back in... being chased by a hungry dog-fish.
In 9, almost every stage has one. There are people fighting on the background bridge in the Pit, people are lowered into the Acid Pool throughout the battle, business is continuing as usual in the Forge...
Portal 2 has three types of this trope. Act One has the various advertisements for Aperture Science products (the Thermal Discouragement Beam was apparently developed to prevent employees from moving from their cubicles), while Act Two has both the not-at-all-helpful signs posted around the place (Know your allergens: Pollen, Animal Dander, Plastics, Antimatter) and the hidden instructive recordings by Cave Johnson ("Best case scenario, you get superpowers. Worse case, some tumours, but we'll cut those out."). Act three is a bit more serious than the rest of the game, but in one test chamber you can see one of the co-op robots running through a door in the distance.
Half-Life 2 contains a few if you know where to look. The easiest to find is just after meeting up with The Resistance at Black Mesa East. While Dr. Mossman takes you on an elevator ride down to Eli Vance's lab you can catch glimpses of how the Vortigaunt aliens help out around the house.
At the beginning of No More Heroes 2: Desperate Struggle, while Travis and Sylvia are talking at a restaurant, a man randomly falls out of the sky and lands on a car in the background. This event attracts the attention of everyone except them.
More of a funny sideground event, but in Persona 4, everyone is having a watermelon and Ryotaro and Nanako talks about how they can't break watermelons open...and Kanji is pulling a salt container out of his pocket and sprinkles his watermelon...
In the Nintendo 3DS Eshop, when you buy a download, progress is shown by little drops/spheres/toroids being moved across a conveyer line and dropped into the box representing your download. Occasionally, the little shopping bag mascot will ride the line and gets knocked off, flying off-screen. They should've had a crash/cat scream gag for it.
The Wii has Mario or Luigi running across the screen collecting coins, or sometimes both of them swimming all over the screen. There are 3 coin bricks that they hit to represent 33% done, 66% done, and almost done. If he happen to be Fire Mario, you can press the A button to throw fireballs.
Triggering these is what makes the Living Books so fun. They are absolutely loaded with these. Tap-dancing pencils, ants playing orchestras, you name it.
Often occurs in the Mario Party games, especially involving the loser of a mini-game with something bad happening to them.
One worth mentioning: In Mario Party 5, after the Squared Away mini-game, the loser(s) is chased by a random herd of stampeding thwomps.
Sometimes, when enemies are still alive in Guild Wars cutscenes (Especially necromancer minions) they start attacking the party members who're supposed to be standing around watching the events unfold. This becomes a funny background event when you see your party members watching characters have a conversation when minions are beating them up.
Life and Death 2: The Brain has someone pouring coffee all over the floor in the background.
Tales of Monkey Island: During the Brotherhood chase in Chapter 3, while Guybrush is asking Morgan for help, you can see Noogie suddenly stop while raising his wooden sword in the air before collapsing, and Guybrush running and passing through him before he gets up and rejoins the chase. So funny.
Near the end of Chapter 4, though not a funny background event, while LeChuck shouts and laughs in glee, "LECHUCK! Arr, this name-shouting is jolly good fun!", you can see the wounded Guybrush sitting against the encased wind idol in pain in the background before Elaine runs up to him, kneels down, and desperately tries reviving him by holding him close to her. So touching.
Some of the minigames in Rhythm Heaven Fever for the Wii have funny stuff going on in the background, like various people leaping to catch kicked footballs in "Double Date" or Mr. Game & Watch fooling around in the factory in "Working Dough".
The end of a later chapter of Kid Icarus: Uprising features a conversation between Palutena and a certain god, but what you're more likely to notice is Pit being distracted with the Great Sacred Treasure... and eventually crashing into the floor with it.
LEGOIndiana Jones: when the senior Dr. Jones is shot and his legs wander off by themselves, they can be seen in the background kicking the head of a fallen Nazi offscreen like a soccer ball.
If you stealthily approach the VIP's house in Arcadia of Modern Warfare 2, you can surprise a Russian soldier inside, who is busy raiding the fridge, despite wearing a full gas mask to do so.
A Black Comedy one in the infamous No Russian level where the player has to maintain his double-agent cover by taking part in a terrorist attack on an airport, gunning down multiple helpless civilians and somewhat less helpless (entirely serious with that statement) police officers for a good bit of the level. After the shooting starts, the flight schedule suddenly shifts all flights to "delayed".
From Mass Effect 2, many players during Thane's loyalty mission are distracted from the person they were supposed to be tailing, since they are too busy watching the random Turian who calmly walks onto the dance-floor and then proceeds to own the room!
Shepard walking into the AI core to find Legion doing the robot.
During Conrad Verner's side mission, asking him how he got his armor will cause the bartender behind him to silently facepalm.
Early on in Arc Rise Fantasia, when L'Arc and Co. are apprehended by General Freya, you can see Niko standing behind her squirming around in embarrassment/nervousness while she talks. When she finally yells "Arrest them!" and the camera zooms out, Niko hunches over and covers his head.
In the original Spyro the Dragon, Spyro will be chasing sheep in the background while the interview is being conducted in the foreground.
The original Poker Night at the Inventory has plenty of these, especially once you knock players out. Most of them will do more or less what is expected of them—Tycho wandering off to the bar, perhaps, or Strong Bad playing the arcade game in the background—but Max will randomly do...things. Like wandering around the Inventory and bothering Strong Bad while he plays. Or gnawing on a stairway banister. Or coming back to the table, but not actually ''sitting' at his seat, resulting in only his ears poking up above the level of the table.
In Poker Night 2, when the camera zooms in on Sam during a showdown you can occasionally see Max jumping down from the ceiling in the background.
Late In "Metro: Last Light" while waiting in a decontamination chamber the disguised Dark One child will wave to one of the soldiers outside of the chamber. Said soldier will smile and salute back.
In the Gran Turismo series, at least in 4 and 5, the Loch Ness Monster◊ can be seen on the Trial Mountain course. She's in the lake to the left of the people in the boat.
Borderlands 2 mostly has Claptrap wandering around behind the player's chosen character, who is posing on a majestic cliff, but he still manages to get into trouble, such as when he encounters a Tremors-like worm Expy. It also has a Running Gag of him unintentionally going over the waterfall in hilarious ways.
One of the more popular forms of entertainment in Deus Ex is bugging conversations, often resulting in this.
In the middle of Bowser's Highway in Super Mario 3D World, there's one wall that you have to kick a soccer ball bomb at to break open. Way down in the water past it, you can see a large 8-bit Luigi (just as he looked in Super Mario Bros. 1) swimming under the actual highway portion of the level.
In Sheep Happens, the backgrounds have lots of things going on in them that change constantly. From simple things like a cyclops eating a bucket of sheep to Charon crashing his boat through the side of a mountain.
At Festival at the Old Temple, a young boy tries to imitate the fighters' moves. His Bumbling Dad tries to do so as well, but keeps losing his balance.
At Underpass, a group of children watch between games of hide-and-seek. A small boy tries to approach the fighters but is held back by his sister.
At Cosmic Elevator, Mecha-Zangief floats around in the zero-gravity environment, before he gets battered around by floating cargo containers.
At Mad Gear Hideout, the hardened criminals are throwing a kabuki festival, of all things. At the end of Round 2, Mike Haggar crashes the party.
At Skyscraper Under Construction, a fat construction worker (an Expy of Mario) is too busy eating a sandwich to notice the fight. When he does notice, he panics and clutches a safety wire for dear life.
At Run-Down Back Alley, a drunk stumbles into the scene, takes a moment to stare at the fighters, and then sits down to enjoy the show.