The increasingly absurd Stock Footage representing the army attacking the monsters. To quote the trope page: "planes taking off, tanks driving away, navy vessels sailing on the sea, cavalry riding across the screen, sumo warriors struggling, baby turtles running across the beach, and Zulu warriors cheering. In that order." In a Brick Joke, the Zulu warriors are seen cheering again when the narrator announces that the Big Bad has been defeated.
Taluca Lake frequently getting injured, including managing to break one ankle, then the other, then both at the same time, while running from the Crawling Spleen.
The alien monster's declaration of his growing strength:
Alien (gravelly): I am becoming ever more powerful!
Taluca Lake and Man Servante: What?
Alien (clearer and more impatient): I am becoming ever more powerful!
Taluca Lake and Man Servante: Oh.
"Shoot the, shoot the little missile thingies at it and then make it go away!"
In "Up All Night", Daggett tries to do a prank call. Not only does he botch the punch line, but Norb sets him up to call their mother:
Daggett: Hey, chicken-neck, you should wear a sweater!
Mom: Dagget, is that you?
Everything in that episode is genius. From "Eat ball, ratface!" to Norb and Dag collapsing into hysterical laughter over thinking the monster from "The Crawling Spleen" was in their house, to the end of "Dag...how long have we been awake?!" is gold.
In the sequel "Up All Day: The Reckoning", Daggett's idea to get to sleep is counting sheep. Instead of counting the sheep himself, he takes the idea literally as he has a whole bunch of sheep counting numbers aloud.
The entirety of "Three Dag Night". Cloning yourself has never been so hilariously fun!
All of "The Big Frog", where after Norbert snaps at Dagget to grow up and stop playing with his baby bunny dolls yest he'll embarrass them. Strangely, Dagget shrugs and complies... and the next scene has him acting like a Bumbling Dad, with over-the-top clothing trends (such as many reading glasses and pants tied up above his waist) and doing all sorts of 'mature adult' things like getting Norb to eat his stew instead of chips (healthy food), swinging his golf-club to work while saying any number but 'four' as he leaves, and literally 'bringing home the bacon'. It's breaking down Norb's normally cool and collected persona... and WORKING.
And much later, Norb starts regressing to a childlike state and playing with Dag's bunny dolls, to which Dag joins in and pretty much states he was doing the whole thing on purpose just to mess with Norb.
"There's an alien invasion in the bathroom!"
Dag's "hook" persona in "Things That Go Hook in the Night". With such tidbits as "Not sharp enough! NOT SHARP ENOUGH! Try it on him! You'll see! YOU'LL SEE!" And:
Dag/"Hook": Sing with us! Sing with us, silly beaver! Sing "The Happy Hook Song!"
(Dag stops in shock) Norbert: DAG! Daggett: Well, uh, remember last week... Norbert: Yes? Daggett: ..when we went to Paleozoic Park? Norbert: Yes. Daggett: He, uh... Norbert: (in realization) No... Daggett: ...kinda... Norbert: (in horror) No! Daggett: ...followed me home. Norbert: Oh no... (T-Rex roars at the beavers) Daggett: I sure wish I'd gotten around to training him, though.
The episode "Up All Night 2: Up All Day: The Reckoning". It perfectly squeezes the sense of your brain stopping to work properly when you're tired and creates a short animated episode full of ingeniously absurd dialogue out of it.
Every appearance of (Dag dressed up as) Muscular Beaver, and the sheer havoc it brings. His apparent superpowers and gadgets are downright wacky even for a superhero, and Dag's representations of them become simply uproarious, from the Cloak of Limited Visibility (conveyed by Dag pretending to hold it up and make "vveeerrreerreerr" noises) to his Razor-Sharp Wondrous...FUR OF STEEL! (one extra-long hair sticking out from his chest). Dag singing heroic music as he "flies" around tops it off perfectly.
The later half of "Chocolate Up to Experience" where Dag is forced to sell a single chocolate bar for $200 all the while Norb gorges himself on a warehouse full of chocolate. As Dag receives physical injuries Norb sends him Ice-Cream Koan messages about being a good salesman, until Dag finally gets fed up after receiving one about quilting that makes no sense at all. When Dag actually does make enough money, he asks Norb when he's going to get his quilt. Norb asks if he'll accept steak knives.
Daggett: "If customer doesn't want pro-duct, make pro-duct what customer quilt."
Norbert's ridiculous inspirational speech in "The Loogie Hawk":
Norbert: Think of your poor old mother wearing bologna shoes and corrective headgear. She thinks small animals nest in boxes of tapioca left under the yum-yum trees for too long, but that's the way she was raised! Rub that on your thighs, Mr. Moto, and see how far it gets you! How do you like them apples?!
Also from "The Loogie Hawk", it's clear that Norbert sent Daggett to be the sacrificial lamb to the Hawk while he stayed in the safety of their dam. Yet he's the one that kept getting spat at while Daggett is safe and takes forever to actually bag the bird. Eventually Norbert does it himself, and then says a few choice words to his brother.
Dag's utterly deadpan response to an overly emotional Bing and Norbert hugging him while wracked with grief over their old relationships:
Dag: Physical intimacy. How I do loathe it so.
In "Zooing Time" Dag devours the cabin Abe Lincoln was born in and uses Norb as a scapegoat when the authorities come looking for him. Norb is sent to live in a zoo, but it turns out the place is pretty much a five-star resort for animals and Norb has the time of his life. There are a few instances that count as single moments alone:
The slightly insane zookeeper who frequently talks to a pen he calls Charlton which he keeps in his jacket.
(The gorilla proceeds to stuff Dag inside a suitcase and then repeatedly slam it between two trees)
Dag's repeated confessions of his guilt followed by an immediate "I wouldn't admit that in court though."
Daggett: I'm guilty! As guilty as a Sasquatch in a pudding factory!
Norbert: "Sasquatch in a pudding factory?"
Dag being forced to act as all the animals that escape from the zoo because of his stupidity, culminating in him dressing in bridal gear and going "Woof."
In "House Sisters" the Beavers are going on vacation and ask their sisters to watch the house for them, and since they can't read decide to make a video for them. Only Dag's ideas for what they can do get more bizarre and maniac, before he finally suggests:
Daggett: Why don't we have them repaint the living room? I like yellow walls with purple polka dots. And they can finish putting together your super electro gizzer blinky. And why not have a disco ball in the living room? And new bunk beds built out of, of candy corn! And then they can put those little white twinkly lights all around the dam, and clean the barnacles off the bottom of your boat, and drain the pond, strip mine the forest and make it a LANDFILL SITE!
Norbert: They're just little girls. WHY DON'T YOU HAVE THEM RAISE THE TITANIC WHILE WE'RE AT IT?!
After ingesting stupidity potion, Dag got smarter, but Norb got stupid. At the end episode, a super intelligent Dag claims he has solved ever mystery in the universe, except that he still doesn't know what happened to Norb. Cut to a scene with Norbert on top of a Mayincatec pyramid, being fed fruit and being worshipped as a god, with the mantra, "DUUUHHH!!!"
Dag and Norb's insanely long staring contest, including Dag's frequent attempts at cheating. At one point, Dag has been staring at Norb for so long he hallucinates that Norb has turned into a dancing pickle, and then whips out a guitar and tries to make Norb cry by singing an emotional song. Dag is forced to stop because the last part "Sounds like a bag full of cats gargling razor blades." He then eats the guitar.
Norbert ends up thrown out of the house window three times in "Daggy Dearest". All because he tried and failed to get rid of the mongoose baby.
Big Bunny acting as a bodyguard. "GET DOWN!" (slam)