Just about every time Pablo has one of his panic attacks. And everybody's complete deadpan reactions to them.
Any time a cartoony sound effect is used:
"Match on Mt. Olympus": Austin pokes Pablo's beak, and a "boop!" noise is made.
"Who Goes There?": Tyrone falls off a chair. If that wasn't funny enough, he makes a squeak noise when he hits the ground, as if he fell on a chew toy.
Anytime one of the kids plays a villain, you can tell the voice actor is having a blast with their lines.
This exchange from "The Two Musketeers":
Tasha: Is that why you don't like the Empress? Because she has a hot air balloon and you don't?!
Musketeers Tyrone & Pablo: Yeah.
What makes this funnier the deadpan manner in which they say it.
The only part of "Scared of You" that might be deliberately scary is a falling staircase that everyone barely survives. Uniqua wants to relive it.
"Cave Party" features a running gag where someone invents something, and the other characters guess the name. Many of their guesses are average, but in one bit, Pablo's guess is bacon.
Much of "Best Clowns in Town". At one point, Pablo and Uniqua come up with the plan of firing themselves out of a cannon to catch up to Tyrone's train. Tyrone tries to slowly back away, and then they grab him and stuff him into the cannon.
From "The Yeti": There's a photo of Tyrone bunny-earing Tasha with the weirdest expression on his face, while Tasha is oblivious. And in the very next pic, he did it again, but this time he got caught.
In "It's Great To Be a Ghost", the crew hear a spooky voice say "It's Great To Be a Ghost", instead of the usual tummy rumble. Pablo then nervously invites his friends to his house, and they eagerly agree, bolting out of the haunted house.
In the episode "Secret Mission", when Tyrone is doing the limbo under a laser, Pablo and Uniqua sing a song that refers to him as a "secret agent limbo moose".
Uniqua and Pablo's arguments throughout "Horsing Around".
In "Ranch Hands from Outer Space", Tasha asks Pablo and Uniqua (who are playing said ranch hands) to build a tall fence. What do Pablo and Uniqua do? They use their alien powers to build a fence that only went up into the air, not around the field.
The entire Festival of Dirt scene from "Robin Hood the Clean", especially the long/short jump part.
These lines from "Pablor and the Acorns":
Tasha: I love hiking in the woods! Its so calm.
Tyrone: Its so quiet.
Austin: Its so peaceful.
(Pablors spaceship crashes down to Earth, nearly crushing the three Acorns)