In the opening sequence, there's a brief montage of the entire main cast hula dancing. Why is this "funny" instead of simply "cute?" Because we truly mean the entire main cast, up to and including Jumba, Hämsterviel, Gantu, and Cobra Bubbles (who even kept his Men in Black suit on and just put on a hula skirt over it).
At the hospital, Lilo, Stitch, and Pleakley are attacked by Gantu, leading into this:
Lilo: Whoa, whoa, whoa-whoa-whoa. Let's be rational here. I think that there's a way everyone can be happy. And that's if we just... calmly... RUN! (She, Pleakley, and Stitch run away) Gantu: How does that make me happy?
Later, when Pleakley is in danger of exploding, Jumba's only concern is that it might be messy. His solution: getting a big towel.
The fears, aside from Nani's nightmare, are kinda humorous like Jumba being afraid of his ex-wife, Pleakley being afraid of his mother, Mertle and her posse being scared of Lilo. Yeah... they have some rather odd fears.
Gantu fails to realize the concept of a sandcastle.
Gantu:(looking up at Stitch's sand made fortress) Open up! I'm here for the abomination! Lilo: Go away, I like abominations. (she, Stitch and Cannonball blow raspberries) Gantu:(facepalms) I'll have to devise an assault plan for this fortified defense structure. (leans against it, his hand goes through wall) This is just made out of loosely-compressed silicones.
When Lilo tells Jumba and Pleakley about Mertle's sand sculptor idea, they unintentionally agree that it is better than Lilo's idea.
The Never Ending Dance that Jumba and Pleakley end up going into. Seriously, they dress up in Disco garb and everything and even sing along to a very odd song.
David and Lilo having a rather childish talk about that results in Stitch eating some turtle wax.
This line in "The Asteroid", after our heroes discover an old hermit on the asteroid, while on a mission to destroy it to prevent it from colliding with Earth. The line isn't just hilariously ironic, it's made even funnier by how nonchalant and blunt Jumba is about it.
Jumba: (cheerfully) Hello, we come in peace to blow up your home.
Stitch unsuccessfully attempting to get in on Lilo's thought process.
Lilo: You look like a hairy hairball... and you seem to like to eat hair... and you're made of hair... so I'm going to call you... Stitch: Hairy! Lilo:(as though the very idea is ridiculous)No! "Clip"! Stitch: Huh?
Even funnier when you consider Lilo is responsible for such past gems as Finder, Nappifier, and Hotcold. She was even going to name Morpholomew, "Changer", which Trixie convinced her not to go with.
When Clip evades Gantu into a bus, he goes into a big Badass Boast about how she will not escape him - complete with lightning - only to notice some kids looking at him and, slightly embarrassed, simply goes, "I mean, I, uh, missed my bus".
Jumba gets very happy when his hair suddenly grows back (as a massive afro). He makes the whole planet shake!
Whenever someone is spiked, they get 99% sillier. This leads to goofy expressions, silly answers at the trivia contest and mindset of silliness. This especially works on Stitch, who acts overly silly with this effect on him.
Most of "Shoe" is funny, thanks to the horrible bad luck the titular experiment wreaks upon the entire cast: the whole thing is Amusing Injuries incarnate. Special mention goes to the scene where Lilo is trying to figure out how to help Shoe, while Stitch watches from the windowsill - by the end of the scene, Stitch has been knocked on the head, fallen out of the window and had his fingers smashed upon trying to climb back in. The best part is the final battle with Gantu, however, which quickly turns into a game of "how bad can their luck possibly get?" High points include Gantu being strapped to a hot air balloon and floating in front of a skeet shooting competition, and a random spurt of lava forming at Stitch's feet out of nowhere.
When 625 tries to reveal one other detail about Shoe, Gantu tells him, "Quiet! I do not want to hear anymore about 113!" It turns into a Brick Joke later on when 625 finally reveals that Shoe is also a good-luck experiment and Gantu asks him why he didn't tell him earlier and 625 reveals that he got their whole conversation on tape, which leads into this:
Gantu on tape: Quiet! I do not want to hear anymore about 113! Gantu: But- Gantu on tape: But nothing! Go make a sandwich! Gantu:(getting angry) You can't talk to me like that! Gantu on tape: Yeah? What are you gonna do about it, trog? Gantu:(takes out blaster and aims it at the tape recorder) Insolent device! Silence! Gantu on tape: I'm not listening! Na, na, na, na-na-na! (Gantu blasts it to pieces)
Under Spats' Hate Plague, Jumba harasses a hotel critic with a full-blown chicken dance.
While Nani is talking to the entire family, Stitch just wanders off while her back is turned and eats one of their potted plants. Cut to Lilo giving him a Death Glare. A few seconds later, Lilo is talking to Nani again and Stitch just quietly spits the plant into the pot.
Heckler (voiced by Will Sasso) spends the entire episode mocking everything about the characters, in many cases hilariously. The gold comes when he takes the mickey out of The Series' nigh-constant use of its two favorite phrases.
Heckler: "Again with the 'ohana' and the 'one true place!' I see you've read the dictionary of two phrases cover to cover!"