Bruce's morning routine is interrupted by an April Fool's Day prank from Alfred. Soon after, however, they learn that downtown Gotham is being overcome by a wave of uncontrollable laughter. The culprit is the Joker, who is using a gas that induces laughter to incapacitate people so he can plunder the city unopposed.
Batman sends a probe into the gas cloud and discovers that being exposed to the gas for too long can drive its victims permanently insane. Soon after, the gas cloud reaches Wayne Manor and Alfred is affected as well.
Batman tracks down the garbage barge Joker is using as a cover to spread the gas. Joker briefly incapacitates him and throws him into the river. However, Batman is able to escape and follows Joker to his secret base at the city dump. Batman quickly disables Joker's henchmen, then pursues Joker himself on a long chase through the dump's inner workings before finally capturing him.
Back at Wayne Manor, Bruce consoles Alfred over the mayhem he caused while under the effects of Joker's gas. He then gets back at Alfred for the morning's prank with an April Fool's joke of his own.
Tropes in this episode include:
- Actor Allusion: When Batman emerges onto the Joker's ship with a breathing apparatus and stares right into Joker's periscope, we hear Vader Breath. Guess Return of the Jedi wouldn't be Mark Hamill's last time hearing that particular breath.
- April Fools' Plot: The episode takes place on April Fools' Day, an early scene featuring Alfred "drawing Bruce a bath" (on a piece of paper). Bruce retaliates by the episode's end by pretending he plans to take the priceless Ming vase Alfred broke out of his salary.
- Art Shift: The animation is noticeably more rubbery and cartoony than most any other episode (par for the course with AKOM) which actually fits as an April Fool’s episode with the Joker.
- Berserk Button: Joker really is outraged over the "death" of Captain Clown. It's possible he's more mad that his presumably very expensive robot got destroyed.
- Book Ends: The episode begins with Alfred drawing Bruce a bath. After dealing with the Joker's shenanigans with the garbage barge, Alfred draws Bruce a bath for real just to get rid of the stench.
- Breaking the Fourth Wall: The Joker goes out of his way to tell the viewer as he readies to loot the financial district, “When the going gets tough... the tough go shopping!!!”
- Cape Snag / Giving Them the Strip: A version of Batman's detachable clasp is shown when his cape becomes trapped in the grip of a robot Joker henchman—Batman quickly detaches his cape and spends the rest of the episode capeless.
- Cut Lex Luthor a Check: Joker creates a submarine with a trash barge over it that profusely emits his laughing gas along with a fully functional killer robot... and robs one diamond truck and loots a couple stores in the financial district. Justified in that driving Gotham mad could easily be the main objective and any looting involved is just a bonus.
- Determinator: Captain Clown takes a ridiculous amount of crowbar shots to the head. Being a robot helps with that.
- Disproportionate Retribution: Inverted; after Batman destroys the Joker's pet robot, Captain Clown (which Joker considers murder, since Captain Clown was his best friend), Joker retaliates by... dumping a crane full of smelly garbage right on top of Batman.
- Hoist Hero over Head: Captain Clown lifts Batman over its head and starts spinning him around very fast before dropping him in a trash can.
- I Know Kung-Faux: One of Joker's goons tries to intimidate Batman with quasi-martial arts posing, yelling, "Hi-ya!" Batman effortlessly puts him down in about 3 seconds.
- Large Ham: The Joker gets a few extra-hammy lines: "You KILLED Captain Clown!!!!" and "You're going to melt just like a grilled cheeeeeeeeeeeese sandwich!!!"
- Mecha-Mook: The "Captain Clown" robot piloting Joker's laughing-gas barge. Also a Giant Mook, given its strength.
- Modesty Towel: Bruce walks to the bathroom in a towel when Alfred plays his April Fool Prank on him.
- No-Sell: Captain Clown is a rather durable robot; Batman hurts his fist trying to sock it, and in a later scene, even whacking it upside the head with a crowbar barely slows it down. Eventually, he has to lure it to some heavier machinery—a trash compactor—and manages to crush it.
- Not So Stoic:
- Joker is dangling over the fire and pleading to be saved. Batman would never just let him fall, but he's okay with pretending to consider it and hearing him beg first.
- At the beginning of the episode, Bruce is nonplussed over Alfred’s “drew you a bath” gag, prompting Alfred to say, “Not a funny bone in that man’s body.” At the end of the episode, he suggests garnishing Alfred’s pay “for a couple of years” to pay for the vase he broke while affected by the gas-only to note he’s just trolling Alfred.
- Priceless Ming Vase: Alfred, under the influence of the laughing gas, smashes a Ming, and is even prepared to accept being docked pay from Bruce Wayne as punishment.Bruce: Don't worry about it. I'll just take it out of your salary for the next couple of years.
Alfred: [Oh, Crap! face; then, resigned] Yes, sir.
Bruce: Alfred... April Fools. - Punch! Punch! Punch! Uh Oh...: When Batman realizes that Captain Clown is really a robot.
- Robotic Reveal: If the constant whirring every time he moved didn’t give it away, Batman eventually destroys Captain Clown’s Mask to reveal a robot underneath.
- Save the Villain: Lampshaded when the Joker is hanging over a pit of molten metal.Joker: Batman! You wouldn't let me fry, would you?
Batman: [considers it]
Joker: BATMAN! [Batman pulls him up] - Scrubbing Off the Trauma: After the battle, Bruce comments that he still feels "soiled" from the garbage the Joker dumped on him even after taking several showers.
- Shout-Out: After dumping Batman underwater, Joker turns to Captain Clown and says, "Well, Captain, this could be the start of a beautiful friendship!"
- Shower Scene: After Alfred pranks Bruce by "drawing" him a bath (on paper), Bruce hops into the shower instead, then leans his bare torso back out to ask Alfred to turn on the radio.
- Soundtrack Dissonance: The episode has a rather minimalist soundtrack: a drum machine straight out of a really dark hip-hop video, with the Joker's regular theme interrupting throughout. It's actually very unsettling.
- Where Does He Get All Those Wonderful Toys?: It's a mystery where Joker obtained a robot of Captain Clown's quality, and a submarine.
