The Trailers for the film in which Stitch disrupts the Award Bait Song scenes from other Disney films. Such as Beauty and the Beast, in which Stitch crashes the chandelier, the Beast and Belle roll out of the way, Belle huffs "I'll be in my room!" and stomps off, Stitch giving off a Wolf Whistle as she passes by, saying "get your own movie!"
Stitch stealing Jasmine from under Aladdin's nose, with the princess strangely interested in the small fuzzy alien. Poor Ali.
Then there is also Stitch surfing in just as Ariel is about to sing "Part of Your World" with the waves crashing behind her... pause it at the right time and her face is just priceless.
Lilo: (on the phone with Bubbles) Cobra Bubbles? Aliens are attacking my house. They want to steal my dog. (pause) Oh good, my dog found the chainsaw! Bubbles: Lilo! Don't hang- (click)
After Lilo tells Stitch to build something and he sets out creating a scale model of San Francisco.
Lilo: (completely deadpan) Wow. San Francisco.
Then, after Stitch goes on a rampage and destroys the whole model:
"No more caffeine for you."
Just prior to this, Stitch going berserk all over Lilo's room... only to be calmed down when she just puts a lei around his neck◊.
Stitch learning to dance.
When Cobra confronts Nani about losing her job, Stitch walks up behind Nani while holding a book. He stares innocently at Cobra for a moment, growls and, without any provocation at all, chucks the freaking book at Cobra's face.
When one of the lenses of Cobra's sunglasses pops out as a belated reaction to the hit.
The look on David's face when Lilo asks him to give everyone a lift to the shore - Lilo, Stitch, Nani, Pleakley, Jumba, and Gantu (although the last one is probably big enough to just wade).
Uhh...sure. But I'll have to make two trips.
Shortly after this we hear David talking to Stitch, and we hear him saying:
David: So you're from outer space. I hear the surfing there is choice.
"BLUE PUNCH BUGGY!" Stitch (whacks Jumba with a blue punch bug car, owner: Nani) "NO PUNCH BACKS!"
Pleakley discovering the dietary habits of Earth's most "endangered" species which is later revealed to be a ruse by Cobra Bubbles.
Pleakley: (gasps) Don't move! A mosquito has chosen me as her perch! She's so...beautiful...look! Another one! And another one...why, it's a whole flock! And they like me! They're nuzzling my flesh with their noses! And now they're, uh...they're...(camera cuts away to an aerial view as Pleakley gets swarmed by them) WAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH!
This exchange, when Nani first sees Pleakley and Jumba in disguise:
Nani: (to Pleakley) Your head looks swollen.
Jumba: Actually, she's just ugly.
After Stitch steals a tricycle, Jumba talks about how his programming will draw him to large cities, where he'll causes chaos (back-up sewers, reverse street signs, steal everyone's left shoe.....). Stitch cycles around the island trying to find an city, only for Lilo to tell him that there isn't one and he has a fit.
When Pleakley criticizes Jumba for almost shooting Lilo, lectures him on the Mosquito food chain, and gives the viewmaster toy to him that he used earlier to show the Grand Councilwoman Earth. It becomes clear that Jumba cannot see into it because his eyes are too far apart.
A bunch of white tourists were treating Lilo like an animal in a zoo, so she timed a rant about tsunamis and how they're giant waves that "move faster than the speed of sound" and tsunami sirens being your only warning to a siren test. She yells "TOURISTS, PREPARE TO DIE!" incredibly dramatically... and then the sirens go off. All of the beachgoers (plus Jumba and Pleakley) run like hell.
This dialogue during Jumba and Stitch's fight:
Jumba: Come on! What's the big deal?
Stitch: Inga tu shmeeshta!
Jumba: I'll put you back together again. I'll make you taller and not so fluffy!
Stitch: I LIKE FLUFFY!
And after Jumba tosses plates through the ceiling which Stitch is on, Stitch says something in alien that vaguely sounds like a Your Mom insult and Jumba's hilarious response to it:
"Oh, leave my mother out of this!"
Nani gets fired from her job after Stitch attacks Pleakley:
Lilo: Did you lose your job because of Stitch and me?
Stitch takes a rather unflattering picture of Mertle, and mocks her under his breath with a "Bleh!" before tearing up the photo.
Also from Stitch Has A Glitch: Lilo attacking Mertle for saying she'd never be like her mom with Stitch taking pictures. And no one can say Mertle doesn't deserve it.
What doubles the funny of this moment is that after Mertle makes her remark, Lilo turns to Stitch who puts up his hands to stop restraining her as if to say "There ain't no way I'm stopping you after that, go ahead!"
The scene directly afterward when Lilo's kumu hula makes a visit to the house to talk to Nani about Lilo's behavior. Lilo deadpans to Stitch, "Next time, flush the evidence." Stitch responds by miming flushing a toilet and making a "ka-shush" noise.
This exchange. Lilo and Stitch are at their wits end looking for an idea for Lilo's hula, when randomly a chicken walks by. Lilo goes from depressed to excited so quick, and Stitch is so blunt yet gentle about it that the timing is just hilarious.
Lilo: <jumps to her feet> "That's it! I've got it! Elvis is trying to tell us to do a hula about a chicken!"
Stitch: <gently touches her shoulder and eases her down> "No, he's not." <Lilo sits back down>
The way the chicken clucks after Lilo announces her "idea." It sounds absolutely bewildered.