Calvin and Hobbes hold a special G.R.O.S.S. meeting - it's both the club's second anniversary and their millionth water balloon attack on Susie. Unfortunately, just as he fills up a water balloon, Susie is splashed by someone other than him - and his mom won't believe him. Naturally, Calvin investigates the crime as Tracer Bullet, along with the less willing Tiger Eye.
Their first suspect is Socrates, who uses his security cameras to prove him wrong (though he's oddly reasonable while denying it). He ends up proving Sherman innocent by himself, and obviously Moe merely Megaton Punches him... so who's the culprit? Worse yet, Susie gets splashed three more times after he visits each suspect.
Then Calvin realizes - Hobbes had disappeared every time Susie had been splashed - he's the culprit! He angrily confronts him and belts out a "The Reason You Suck" Speech, the other three watching in shock. Suddenly, Hobbes is assaulted with five water balloons. Calvin reveals that the group had planned this all along. Nonetheless, Calvin and Hobbes get over it and go back to being friends, and Calvin gets off the hook thanks to Andy.
- Agony of the Feet: Calvin when he fails to kick the door down.
- Big "WHAT?!": Calvin does this when Hobbes says he's not ready.
- He does another one later in a similar scenario.
- Cassandra Truth: Calvin really is innocent for once.
- Clear My Name: The episode's main plot.
- Flat Joy: "I said, Oh joy. Wonder. Uncontrollable excitement."
- Foreshadowing: Hobbes always comes right after Susie is splashed.
- Insane Troll Logic: Calvin claims that since one of the water balloons was the same color as the ones Socrates had attacked him with last week, then the latter must be the culprit.
- Lame Rhyme Dodge:Hobbes: The one millionth time you've failed a water balloon attack.
Hobbes: I said, dinosaurs lived a million years ago, but McDonald's still fail to make water balloon Big Macs.
- Living Crashpad: Calvin, who rants on it:"It's my world, Hobbes! And I'll stand wherever I want! We have an entire planet, here, and you're welcome to land anywhere on it, but my head! Got it!"
- Medium Awareness: A borderline, Mind Screwy example: Calvin threatens to throw an encyclopedia at Hobbes if he says one more word. He replies "okay", and Calvin claims it's one more word. When Hobbes later replies "OK" (just two letters this time!), he's fine with it.
- Milestone Celebration: In-Universe - G.R.O.S.S. has both its second anniversary and its millionth water balloon attack on Susie.
- Noir Episode: Partly.
- Not Me This Time: Poor Calvin.
- "Open!" Says Me: Calvin attempts to do this. It doesn't work.
- Paranoia Fuel: In-Universe - Hobbes is unsettled by the fact that Socrates has a security camera in his room (which he later disposes of).
- Prehensile Tail: Calvin demands to see Hobbes' tail because he's hiding a water balloon with it.
- "The Reason You Suck" Speech:Calvin: IT WAS YOU! I CAN'T BELIEVE YOU! MY OWN BEST FRIEND WENT AND GOT ME FRAMED! YOU TRAITOR! BENEDICT HOBBES! I'LL NEVER SPEAK TO YOU AGAIN!
Hobbes: Uh Calvin?
Calvin: HOW COULD YOU DO THIS TO ME! I WELCOME YOU INTO MY HOME! I LET YOU EAT MY TUNA! I LET YOU POUNCE ME AND ATTACK ME! I LET YOU BE FRIENDS WITH SOCRATES! I EVEN LET YOU BE PRESIDENT OF G.R.O.S.S! AND YET YOU DO THIS! YOU'RE LUCKY I DON'T THROW YOU OUT ON YOUR FURRY BUTT ON THE SIDEWALK FOR THIS!
Hobbes: Okay, calm down.
Calvin: YOU KNOW WHAT? EVER SINCE I LET YOU INTO MY HOUSE, YOU'VE GIVEN ME NOTHING BUT TROUBLE! I USED TO HAVE A NORMAL LIFE! BUT NOW MY LIFE IS COMPLETELY TOPSY-TURVY, FILLED WITH POUNCES, FIGHTS, CUTS AND BETRAYALS!
Hobbes: Take it easy.
Calvin: BUT THIS ONE TAKES THE CAKE! YOU DELIBERATLY TRIED TO GET ME INTO TROUBLE! I THOUGHT YOU WERE MY BEST FRIEND! BUT I WAS WRONG! YOU'VE CROSSED THE LINE, STRIPES! YOU LEAVE ME NO CHOICE, HOBBES! I AM GOING TO TEACH YOU A LESSON YOU'LL NEVER REMEMBER: NEVER BITE THE HAND THAT FEEDS YOU!
- Rule of Drama: Calvin's answer as to why he has a water balloon when he denies attacking Susie - "Uh... to add to the... drama?"
- Rule of Three: Calvin has three suspects.
- Say My Name: Calvin screams "HOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOBBBBBBBBBBEESSSS!" when he figures out that he's the culprit.
- Screw This, I'm Outta Here!: Ends up being instrumental to the plot's conclusion.
- Season Finale
- Title Drop:Calvin: Huh. I could have sworn we were on a very important mission...
Hobbes: I'm drawing a blank.
Calvin: NOW I remember! We were on The Case of the Rogue Water Balloon.
- Vitriolic Best Buds: The closing remarks of the episode are the narrator noting Calvin and Hobbes as this.
- Wide Eyes and Shrunken Irises: Calvin gets these when he realizes the true culprit.