- Safety Sammy, period.
- As Rancid Rabbit imprisons the citizens of Nearberg for not having a license for whatever species they are, he finally makes it to Mr. Sunshine at whom he pauses for a while, trying to figure out what he is exactly. Finally he simply states he's under arrest for not having a license.
- As the duo set fort in their room awaiting the arrival of the horror monster, Toothpick Head, they watch as a plethora of other horror movie monsters appear in their room doing generally silly things (eliciting no reaction from the duo besides a laugh from Dog).
- And the toothpicks? There's hundreds and thousands, and... millions of them...
- "I HAVE CHOCOLATE"
"Thinking is fun! It makes the brain happy!"
- The educational tape:
"Hi, Happy Brain!"
- "You...you did this to me, bow-wow person! You made the smarts go bye-bye!"
- "Hey, I using that brainie!"
- When Cat first starts losing his brains, he tries to get smart again by watching one of Dog's educational videos. Except...he doesn't know how to fit a tape in a VCR anymore, and ends up smashing it to bits.
- The episode "Party Animal", especially the roller coaster scene.
- In The Great Parent Mystery, Lube heads to the Parents Day celebration with parrots, mistaking it for Parrots Day. Rancid corrected him, and Lube's parrots fly up with Lube afterwards.
- While Catdog are in an alien spaceship:
Cat: "Dog, do something!"Dog: (does some weird funny thing with his hands)Cat: "What are you doing?"Dog: "I'm doin' something!"
- In "A Dog Ate My Homework," anything with President Rancid is hilarious, but this moment is the funniest: while waiting for Dog to come and eat his speech, Rancid starts to read it. The crowd boos him, and he tries to edit the speech. This doesn't work, so he starts singing "Tea for Two" and dancing to an ever-increasing chorus of boos. There is also this comment after it happens:
Random Senator #1: This is the most embarrassing thing I've ever seen the President do!Random Senator #2: Oh... newcomer, eh?
- Some of the jokes in the background are chuckle-worthy, such as a tour bus saying "Willie Nelson Medicare Tour" in "Hotel CatDog."
- In "Nine Lives", the shot showing the angry mob, which includes the Greaser Dogs covered in cement with a mouse probably moved them, Mr. Sunshine and his cow, and a personification of Earth is quite hilarious despite being in a dark scene in the episode.
- In "Talking Turkey", Lube roasts a map of the country Turkey instead of the bird. Also the balloon guy holding on to a loose Mean Bob balloon is a funny Running Gag in the episode.
- When Rancid Rabbit is the police chief, who receives a call at his desk.
Rancid: (Answering the phone) Stool Pigeon Hotline. You squeal, we deal.
- Cat and Dog imitating Scottish accents in "Shepherd Dog".
- Also Cat managing to sell Dog's talents for "quadruple" the price of the previous sheep dog. He expected money, but it turned out to be Dog Chow (and Dog earned 4 bags of chow instead of 1).
- In "CatDog's Gold" when Lola observes mountain goats, the mountain goats get up in the mountain in hilarious ways with one throwing others to the top and the other even using a hidden escalator.
- The episode where Cat eats "Veronica" the gold fish, he trails down Dog's mouth (since they share the same body) to find "her". At one point, he actually crawls out his own mouth.
Cat: I think I made a wrong turn at the small intestine.
Winslow: Heya Cat-doooh... (sees Dog supposedly eating Cat, turns around and goes back into his room.) Nevermind.
- And later, when Winslow comes to greet them...
- A blink-and-you-miss-it one, but in the episode about Cat's pirate ancestor, Orangebeard, his Pirate Parrot is shown talking like Winslow for some reason.
Pirate!Cliff: FIRE OLD BETSY!
- Also from that flashback:
Pirate!Lube: (to a random old lady) Betsy, you're fired!
- Mondo CatDog in "CatDogumentary". It has funny scenes like a rhinoceros prop falling, CatDog acting like a chameleon and the last scene is a parody of The Lion King.
- In "The End," Cat relates the story of Nostradummy, a prophet who lived thousands of years ago. We see Nostradummy make three predictions: "Mountains will fly. Trees will speak Japanese. And a cat and dog will be joined together as one." The scene returns to the present, and Cat remarks that "one out of three of his predictions came true." Cue a walking tree appearing outside the window and declaring "Konichiwa, CatDog-San!"
- When Cat becomes an alley cat (the cat equivalent to a beatnik) he gets a tattoo on his chest, much to Dog's surprise. The discovery leads to the following exchange:
- In "Pumped", Dog gets super muscular and proceeds to try and beat up the Greasers. Cliff and Lube's reactions to seeing a giant overly-muscled Dog is expected. Shriek's reaction?
Shriek: [with a giant grin on her face] OH MY!
- When a con artist duo disguised as a CatDog stays at the house, Dog sees something suspicious while they're getting back into costume. This leads to this exchange:
Dog: But I thought I saw something weird!
Cat: There's nothing weird about a naked CatDog, Dog! No matter what the kids in gym class said...
- From "Work Force", the original Number One Prize Stuffer becomes so stressed by his constant routine that he finally has a nervous breakdown stuffing himself into a cereal box and getting sent into a chute where the boxes get loaded.
Cat: Well, that's something you don't see every day.
- Also from Work Force, Catdog are standing just before the door to the food court after a tall flight of stairs. A server comes out and trips over Catdog's body, screaming as he tumbles the long way down.
- "Let the Games Begin" opens up with Catdog in jail, and in one sentence explains exactly how they got there.
Cat: That was not a fire hydrant, Dog; that was the dog catcher's leg!
- Pretty much anything Mr. Sunshine says in his trademark monotone. Highlights include his "disappearing act" (read: slowly putting a handkerchief behind his back) or when he acts as the priest to Dog and Shriek's dream wedding, ending the ceremony with "You may now slobber all over the bride."