Joe and Diesel must infiltrate an underground Yu-Gi-Oh! tournament to retrieve the rarest card of all time...
"Playing for Keeps" provides examples of:
- Absurdly High-Stakes Game: In the underground Yu-Gi-Oh! ring, losers are banished to the Shadow Realm.
- And I Must Scream: At the end of "Playing for Keeps", Furuya banishes a fourteen-year-old to the Shadow Realm. Before the credits roll, the crew laughs over it.
- Battle Trophy: An apparently illegal activity among Neo Otaku City's Yu-Gi-Oh! players is "playing for keeps", where the winner of the game gets to keep the loser's rarest/most powerful monster card.
- Becoming the Mask: Joe became an "underground Yu-Gi-Oh! addict" and played for keeps after he was sent undercover to stop them.
- Better than Sex: Furuya calls playing for keeps in Yu-Gi-Oh! better than what he's told sex is like.
- Chekhov's Gun: One of the cards Joe took when playing for keeps, as well as caused the bad guy to turn evil, was a Blue-Eyes White Dragon with a misprint on its ATK points. Joe uses it to defeat the fourteen year-old, its misprinted ATK level much higher than the Super-Saiyan Dark Magician's.
- Does This Remind You of Anything?: Joe wound of developing an In-Universe equivalent of a gambling addiction when he starting "playing for keeps" undercover.
- Drowning My Sorrows: Furuya after Diesel calls him out for playing for keeps in Yu-Gi-Oh!. Parodied, since he's drinking marble soda.
- Esoteric Happy Ending: Invoked. In the "Everybody Laughs" Ending, the Chief brings up the fact that the fourteen-year-old boy is now in Hell. This doesn't disturb the happy ending in the slightest.
- Everyone Has Standards: Diesel is disgusted when she finds out that Joe played for keeps in Yu-Gi-Oh!, a sentiment that Joe seems to agree with.
- Freeze-Frame Bonus: When Diesel is briefed before her mission, a close-up of the Super-Saiyan Dark Magician card can be shown. It is revealed to have 9001 ATK points. It's over 9000.
- Heroic Comedic Sociopath: At the end of "Playing for Keeps", Joe banishes a 14-year-old to the Shadow Dimension. Before the credits, the crew is seen laughing about how the 14-year old is where he belongs. To add insult to injury, the episode ends on this line:And the fourteen-year old's in hell!
- I'll Tell You When I've Had Enough!: In the middle of "Playing for Keeps", Joe gets drunk on Marble Soda. The bartender attempts to cut him off, but Joe wrenches the bottle out of his hands. Due to his inebriated state, however, Joe struggles for about half a minute to actually open the bottle.
- Mood Whiplash: Diesel's capture in "Playing for Keeps" is followed by a "Who's That Pokémon?"-type bumper.
- Nerds Are Virgins: Despite being established as a badass among Otaku, he's still an Otaku himself.Joe: It's just... the thrill of playing for keeps. Nothing comes close. It's better than what I'm told sex is like!
- Revenge: The villain of "Playing for Keeps" is a kid out for revenge against Furuya for taking his overpowered (due to a misprint) Yu-Gi-Oh card.
- Serious Business: The Yu-Gi-Oh! card game is treated pretty much the same as it is in the anime; a universally beloved game where rare-cards are worth more than gold (and often one of a kind) with Absurdly High Stakes, including being sent to what is basically Hell for all of eternity if you lose.
- Teens Are Monsters: The guy who runs the underground Yu-Gi-Oh! tournament and stole the Super-Saiyan Dark Magician was only 14.
- Undercover Cop Reveal: Furuya arrests members of the underground Yu-Gi-Oh dueling syndicate by revealing his trap card.
