Made even better by the stunned look between Batman and Catwoman before he says it.
Later on, in "Inside the Outsiders", there's the Deliberately Monochrome Black Lightning scene in which he blasts Psycho Pirate's creations in the form of innocent civilians (in color) for doing something he hates. ("Sprinkles? In coffee?!What are you, a six-year-old?!" "So, you're the reason why I had to replace my high tank top in the first place, Mr. I-Forgot-To-Scoop-It-Up!" "Again?! I told you, no white after Labor Day!!!" "How can I be calm when this[points to a "How to Make Pig Smells IV" on the billboard] is forcing me to watch it at a movie theater near me?!") It's so hilarious when he fights.
And near the end, when Psycho Pirate is feeding on Batman's rage, the Dark Knight escapes by thinking happy thoughts and smiling while he pummels Psycho Pirate to a pulp! What a hilarious fight scene!
In "Clash of the Metal Men!", Helium, a living mass of helium gas, swirls around Batman so that he inhales some of it.
Batman: (*in a squeaky high-pitched voice*) "Your time will come, evildoer!" Helium: That's never not funny!
Angry!Batman to Slacker!Batman: "Batman does not eat nachos!" Slacker!Batman: *very pointed munch*
The entire episode "Aquaman's Outrageous Adventure!", where he goes on a roadtrip with his wife and son, but keeps sneaking off to go on adventures. Every time he encounters a new hero, we get a titlecard that uses the Superfriends scene transition noise. It enters a whole other dimension of funny when, after Mera catches on, AQUAMAN promises that he's going to have a vacation with his family... followed by a titlecard for that.
At one point, AQUAMAN tries calling Batman for something to do, and catches him in the middle of beating up mooks.
Batman:(After just tossing a mook off a ledge, he grabs his phone from his belt; answering) Batman!
Later in the episode:
Mera: Why are we going to Gotham?
Aquaman: (Gunshots in the distance) Because, my precious coral, Gotham City is one of the continent's oldest and most historic surface settlements. It's a center of world art, culture, and commerce. (woman screams) Windows up!
Joker teaming up with Batman in "Game Over For Owlman" was bloody hilarious. Highlights include Joker accidentally unleashing sleeping gas on himself whilst fooling around with the Batmobile's controls, shouting "To the Batmobile!", deciding which weapons he can and can't use after Batman makes him promise not to hurt anyone and telling Owlman that they (him and Batman) "don't make deals with criminal scum!"
Best of all, making bunny ears on Batman's dramatic entrance shadow.
And during the climactic battle, while all of the heroes and villains are fighting epically, Joker is running around in the background cackling and holding up a bomb a la Adam West.
It's momentary, but there's a snippet of a scene where various heroes are being coordinated to try and pin down Batman after Owlman's been making him look bad. We cut to a jubilant Plastic Man on the phone, taking long, bouncy strides towards the source of trouble—at which point Green Arrow very bluntly says he's not needed. Plastic Man visibly and audibly deflates (literally) and mopes back offscreen the way he came. It's at once sad and hilarious.
In "The Siege of Starro Part Two", after Starro is defeated by a combination of B'wana Beast's powers dividing him and Alloy's strength, Aquaman says, "I shall name this adventure... 'THE TIME THE C-LIST HEROES BARELY SAVED THE DAY'!!!"
In a similar vein to the one above, "I think I shall call this adventure 'THE TIME BATMAN SENT US TO THE WRONG ISLAND!'" It's just so funny to see AQUAMAN being sarcastic, but in an odd form of deadpan humor where he doesn't change the tone of his voice in any way from any of the other adventures.
A Sherman Tank driven by the ghost of a Confederate General does a Dukes Of Hazzard-style jump over a drawbridge, horn and all.
Just for the record, that was The Haunted Tank from DC's military comics, and it was being driven by General Jeb Stuart.
A second example from that episode would be Joker using his powers to render Harley Quinn mute. Every time she tries to say something it appears on a silent movie-style title card, complete with organ music. This is followed by Harley and Bat-Mite using this to their advantage, by pulling the title cards from the screen as they appear and using them as weapons. Harley even gets one when she blows a raspberry!
"Apparently, my center of gravity is now much.... higher."
Plastic Man's warped sense of history in Cry Freedom Fighters, followed by him reviving Uncle Sam by leading everyone in a muddled version of Yankee Doodle, complete with bouncing ball onscreen lyrics. The writers must have realized how Narmy the moment would have been if it wasn't played for laughs, so they really went all out on it.
From that same episode, the end where Plastic Man doesn't even recognize Barack Obama.
Almost everything Ice says in Darkseid Descending.
Everything Ice says PERIOD.
"I bet you say that to all the Nordic ice goddesses."
Bat-Mite in the Scooby Doo segment of "Batman's Strangest Cases": "Look at this. Someone mispainted Batman's neck! I hate that..."
More hilariously is the fact that he missed an incorrectly painted Bat-symbol in the same scene.
It was mentioned in the Awesome page, but bears repeating here: Joker and Penguin getting the crap beaten out of them by Shaggy and Scooby-Doo!
Bat-Mite fast-forwarding through the intro.
Bat-Mite: Let's just get on with the show already!
In "The Malicious Mr. Mind!", Batman is hit with a age-reversing ray and spends the episode getting younger. After solving the woes of the Marvel family, he is thanked by the Captain himself. Batman's response?
(flashback starts, with Jimmy as a giant monster, destroying a bridge)
Superman: "Jimmy! I told you not to experiment with that growth ray! It's turned you into a super-menace, and now I must remove you from the Earth!"
(Jimmy roars as the scene cuts back to a still smiling Jimmy)
Or there's the part earlier where Batman is talking to Lois about Superman's strange behavior. She Flashes Back to Supes having a barbecue on the beach with Lana Lang, telling Lois "Serves you right for all those schemes you used to try to get me to marry you!" What really sells the moment is when we cut back to the present and Lois quickly says "I have no idea what he was talking about."
Alternatively, there's how Superman defeats Silver Age Mr. Mxyzptlk. He tells him a knock knock joke.
Speaking of Super Dickery references, "Emperor Joker" begins with the series's own take on the "Rainbow Batman" story, complete with the lines on the comic's cover repeated word-for-word.
Remember how funny it was when Joker teamed up with Batman? Well "Joker: The Vile and the Villainous" has Joker in Batman's shoes teaming up with other villains. Complete with his own Joker-fied versions of Batman's gadgets. And his own version of the theme song.
It gets better. Due to Batman being the villain of this episode, they make him sound like an over the top supervillain, talking about his master plan.
Batman: Fisherman! You'll never stop my master plan!
Atom: "Well, I hope you called the most intelligent and quick-witted hero you could find!"
Plastic Man: "Are you seeing what I'm seeing? Cause I'm seeing gorillas... riding pterodactyls... with harpoon guns... stealing a boat."
Batman: "It's Gorilla Grodd."
Plastic Man: "It's messed up is what it is!"
In "Night of the Batmen!", Batman requests that his injury be kept secret. Then Plastic Man calls, saying he heard about it because Aquaman already wrote a memoir about it — and had done book signings and TV interviews.
Plastic Man: "I called as soon as I heard. How ya feelin', Bats?"
And let's not forget Plastic Man's reaction to Catwoman!
And just as funny is Catwoman's angry, almost disgusted response upon seeing that he's not the real Batman, because the reason she got her new outfit in the first place was specifically to get that reaction from Batman himself.
Deadshot's reaction to Green Arrow throwing a batarang at him, only for it to clatter harmlessly onto the ground.
"So, you think you're tough, huh? Do ya, punk?! Well, you don't know who you're dealing with! I am Doctor Ryan Choi, and you are going down!" (his "opponent" is revealed to be a chalkboard full of calculus equations; he adds a minus sign to one) "Ha! How do you like that?! I JUST INVERTED YOUR EXPONENTIAL INTEGRAL!" (adds a minus sign to another equation) "Does it hurt?!" (pelvic thrusts)
Superman pretending to put a straw up his nose while having dinner with Batman and Wonder Woman.
Joker pretending to be an Amazonian.
Lex throws a hunk of kryptonite at Superman. Superman redirects it into the lead-lined sewer. Owned.
Aquaman's phone call to Ryan Choi, where Aquaman suggests he travel over the phone line like the Atom would. As Choi explains that's not his power and that they're talking on cell phones, Aquaman sneaks through the door (tip-toeing) and surprises him.
While miniaturized in the jungle, Aquaman suggests summoning help. As Choi complains that there's no sea life nearby to summon, two Silverfish suddenly appear.
Aquaman: A fish is a fish.
Anytime Blue Beetle argues with his suit is hilarious but the true crowning moments of funny come when the thing just takes over.
Batman: (about the random wormhole the suit is making) Has this sort of thing happened before?
(flash back to Blue Beetle rescuing a cat from a tree, his arm suddenly turns into razor blades that shred all the leaves off the tree and the cat jumps down and attacks him)
Blue Beetle: (quickly) No!
Or that wonderful speech Blue Beetle gives to the little squishy aliens in the first episode, ending on the triumphant note: "NOW WRAP IT UP!!!"
Jaime fawning over Huntress is his funniest non-suit related moment.
In the Sherlock Holmes episode, Holmes' detective skills were more-or-less reduced to an Informed Ability. So in the sword-fight with Craddock, he brags that his reflexes are just as sharp as his mind... and is soundly walloped seconds later, after looking at his sword in confusion◊.
It's probably not intentional; Craddock hits so hard he was checking his sword for damage. Still funny if you imagine his internal monologue. "This guys going to be a tough custo—OW! Jeez, is my sword okay? Did he hurt you, Baby?"
How about the time The Atom is trying to explain to Aquaman in Journey To The Center Of The Bat!?
In "Menace of the Madniks", Booster changes the past, and returns to the present to find the city a wasteland with a giant energy monster. Batman shows up, calls his name, and he promptly denies anything is his fault. Batman says he was just going to ask for help with the monster.
Batman: Wait...you've been meddling in the past again, haven't you?
Later on, Booster proposes several solutions to the problem.
Batman: I am not explaining the intricacies of time travel to a man without a library card!
A great one in "Gorillas in Our Midst" when Gorilla Grodd takes over Gotham and Detective Chimp nearly gets run over. Batman's completely flat delivery totally sells it.
Blink and you'll miss Abe grabbing the axe from the rack marked IN CASE OF EMERGENCY OR CONFEDERATE CYBORG ATTACK.
In "Long Arm of the Law" Kite Man is explaining his origin story. Batman sums it up nicely in a deadpan way only Diedrich Bader could pull off.
Batman: I see. The lightning bolt caused an emotional trauma that made you commit kite related crimes.
The entirety of "Time Out For Vengeance!" episode. Somebody tries to wipe out every Batman in history... and it's both Awesome and funny, because there's not only present day Batman, there's Cave-Batman, Pirate-Batman, Gladiator-Batman and Robo-Batman. And then they team up with each other. It's every bit as awesome as it sounds.
Aquaman's sheer happiness that he gets to fight Romans.