My ideas were
Gotcha! - LSP writing in her diary about how hot Finn is
You made Me - Bonnie's lemon uncle is making an effort to play games with the kids again, but he's an over barring rules lawyer.
The struggle between the RP aspect and the actual mechanics of the game. The DM can deal out bonuses for good RP, which is probably a game mechanic in this.
The Lich/Finn the Human/Jake the Dog - Finn and BMO's older brother Billy is back (he'd be an expy of Chris from Bravest Warriors) visiting from college and DMs a session. Fun times had by all. Basically he plays Billy until he reveals he's actually the Lich and blows their minds. His new character is Prismo.
All Your Fault - Lemon uncle runs a different system and it's like Trail of Cthulhu. Jake wants to nope out, but Finn and Bonnie won't let him.
Dungeon Train - Finn gets way to into pre-made cookie cutter campaigns.
Billy's Bucket List/Wake Up - Billy bro is back again, more fun times are had, then some bad rolls are made. "Welp, looks like my character died again."
Little Brother - Finn and Jake do a one-shot session for BMO, who does surprisingly well.
Everything's Jake - They stay up too late watching old monster movies.
Is That You? - Billy bro is back again, Jake has a confusing plan to bring his character back.
Evergreen - Lady tries her hand at being the DM for a one-shot session and kills 'em all. Rocks fall everyone dies style. One big rock.
Dark Purple - Billy is running a session with his GF at college using random characters. His group would be like expies of the Bravest Warriors.
The Comet - Lady's philosophy from Korea confuses everyone.
Elemental - LSP feels like no one takes her character seriously and tries rolling up a new one, but her new character has terrible charisma.
Two Swords - BMO makes a character who is pretty much a Finn clone. He's about at that age that Finn was at when he made his current character.