Nappa: So, do you like yourself? Vegeta: Yes, of course. Nappa: See? That makes you a hipster. Because... no one else does. Vegeta: (Laughs loudly)
A God Am I: Nappa jokingly implies this a couple of times.
In Castle Crashers when he's riding on the crocodile he wails on a small horde of enemies with ease:
Nappa: Look at this shit! I'm a fucking God!!!
Then in Magicka, when Vegeta gets killed again and Nappa has to revive him for the hundredth time.
Nappa: Luckily I'm around to be your.....hehe.... I feel like I'm your Jesus at this point. I was gonna point out the irony of me constantly saving you, bringing you back to life. Vegeta: Shut up Nappa......
Krillin assumes this in Outlast after a glitch makes him immune to the mad doctor's attacks. It's worn off by the next installment, to his dismay.
Then at the end, when his character is murdered at the end of the game, and after the fadeout it's suggested he becomes a zombie possessed by the Big Bad's spirit.
Vegeta chanting "Minemineminemineminemine" while grabbing ammo or activating Krieg's Buzz-Axe Rampage in Borderlands 2.
Krillin's commentary on Outlast. "'Your only options are to run, hide or die.' Hurray! Back to Namek!"
When Krillin saw Gohan's haircut in Season 2 he remarked that he looked like a young Moe Howard; Gohan retorted with "Well, look who's talking, Curly!" During the LPs he now tends to go "Whoop whoop whoop!" just like Curly did.
Trunks gets mentioned in Dungeonland, and Bulma gets a mention in Dead Sky. Bulma gets mentioned by name in Portal2.
Call Forward: Vegeta's unconvincingly-denied fear of worms in Dead Sky (he and Goku meet a whole family of giant worms during their Fantastic Voyage Plot, and he nearly pukes).
Catch Phrase: Krillin has "I don't like this... I don't like this at all."
Comedic Sociopathy: Most episodes have either Vegeta taking gleeful joy in killing his enemies, him and Nappa happily reminiscing about the various worlds they've slaughtered, or both.
Krillin takes surprising delight in stomping people, enemies and corpses alike. In Part 6 he's surprised about not getting stuff when he kills a bunch of aliens. "These things are like undead pinatas!"
Jump Scare: Krillin gets very, very sick of them during Outlast. "WHY DO PEOPLE FEEL THE NEED TO DO THAT?"
Laser-Guided Karma: In Portal 2 Vegeta doesn't tell Nappa that he needs to use portals to get to the other side of two moving platforms, worked by a laser guided cube. When Vegeta figures it out, Nappa gets his revenge by taking the cube off.
Vegeta (panicking): NO! NO! NO! NO! PUT IT BACK ON! PUT IT BACK ON! PUT IT BACK ON! PUT IT BACK ON! PUT IT BACK ON! (Nappa throws the cube into the polluted water)I'M GONNA KILL YOU! YOU SON OF A BITCH! (Vegeta's character ATLAS drowns and short circuits in the polluted water)
Motor Mouth: Krillin, who admits he's "twitchy" when he's scared.
Not so Above It All: Vegeta constantly seems annoyed by Nappa's childish antics, sighing in resignation often. Then along comes the Portal 2 playthrough, where he joins in when Nappa hums or sings tunes. Vegeta even seems to cut Nappa off in order to get to say "TURTLE POWER!" when Nappa hums the tune to the 80s TV show.
Parental Neglect: Trunks gets mentioned a few times. Vegeta completely ignores him.
Vegeta: Apparently I have some like kid or something now. It's weird. Nappa: Did you name him Vegeta like your father always wanted? Vegeta I don't know what the damn thing's name is!
Rock Falls Everyone Dies: The beginning of Borderlands 2, which features the four main characters getting blown up in a train. While they're supposed to survive, the players (who play DLC characters Gaige and Krieg respectively that are not in the opening cinematic) treat them as dead for good.
Throughout the entire Killing Floor playthrough, Vegeta determination to have fun slowly wanes into desperation until the very end, where he's screaming angrily that they're having fun, while Nappa is sobbing and begging for it to end.
Krillin, by way of Vegeta locking him and forcing him to play Slender: The Arrival, has shown this in spades throughout the playthrough. It's very noticeable during the second episode, when he survives a 17 minutes of a full-aggro Slender Man after he has trouble finding the last page.
The end of Outlast had him screaming "TASTE MY VENGEANCE, MOTHERFUCKERS! AHAHAHAHAHAHAAA!"
Sir Swears-a-Lot: Vegeta, and how. Nappa's got a bit of a foul mouth too, but not as bad as Vegeta.
Krillin has quite a mouth on him as well, especially when he's panicking and running from or taunting his pursuers.
She is Not my Wife: Nappa asks in Dead Sky what Vegeta would do during a zombie invasion, and Vegeta responds that he'd leave the planet. Then he asks what would happen if it happened on earth where Bulma is, thinking she was his wife, and Vegeta denies their marriage with a "Ha!"
Vitriolic Best Buds: Nappa's convinced that he and Vegeta are this, though Vegeta doesn't do anything to show that he considers Nappa a pal. However, Vegeta does seem to show less contempt towards Nappa than he does in Dragon Ball Z Abridged's first season.