Lilo and Stitch are grocery shopping at Mrs. Hasagawa's stand—with Stitch going crazy after eating Kona coffee—when Mertle passes by with her new dog, saying that they are going to compete in a junior dog show in Honolulu. Calling Lilo and Stitch "riffraffs" as she heads to a pet salon, Lilo convinces Nani to let her go to the big city to enter Stitch in the same competition. Meanwhile, Gantu recently found out that an experiment has been activated, and decides to follow our duo to the city in hopes of being able to find it.
In Honolulu, Stitch notices the big city and is ready to cause destruction—that's what he was originally programmed to do, after all—but Lilo convinces him not to because he is good and their main concern is beating Mertle in the dog show. Lilo and Stitch meet up with Mertle and Gigi at registration, and when Mertle insults the duo like she normally does, Lilo decides to enter Stitch in all three of the dog show's competitions (agility, retrieving, and best in breed). Lilo also convinces Mertle to enter all the competitions, too.
The next day, Lilo and Stitch compete in the junior dog show at a local arena while Jumba and Pleakley go sightseeing around the city, with Gantu keeping close by the latter two in hopes of finding the experiment. Stitch does incredibly well in the agility competition, but loses it to Gigi when he accidentally launches a St. Bernard onto the main judge. At ʻIolani Palace, Jumba and Pleakley notice Gantu and decide to keep a watch on him.
Back at the dog show, Stitch is doing well in the best in breed competition. Mertle then notices a coffee stand and asks for the strongest coffee available. She swaps Lilo's water bottle with a bottle filled with a bottle filled with the strong coffee, causing Stitch to lose his all his self-control, as well as the competition to Gigi. Suddenly, Gantu arrives at the arena, terrorizing the people inside as he fights Lilo and Stitch to find the experiment he's looking for. During the fight, Stitch cause Gantu to fire his plasma blaster towards the ceiling, causing the roof to collapse on Stitch, the debris pinning him down. Gantu then finds Mertle and Gigi and takes the latter, because it turns out that Gigi is Experiment 007, one of Jumba's early experiments who is designed to annoy people with her shrill barking.
Just before Gantu could walk out of the arena with the experiment in hand, Lilo then squirts more coffee in Stitch's mouth, giving him enough energy to break himself free. He stops Gantu from taking Gigi, throws the big dummy out of the arena, and saves his "cousin". One of the judges who was still in the arena chants "Best in show!" in regards to Stitch. Mertle, in a rare moment of gratitude, decides to give Lilo and Stitch the trophy, claiming that she doesn't need it to prove that she and Gigi are the best because she "knows" it anyway. Lilo decides that she doesn't need to contain Gigi in order to find the one place where she truly belongs, because "the little yapper" already found its home with Mertle.
Back home on Kauaʻi, Nani shows Pleakley a large amount of bills, telling him that he owes money for charging with his twenty-eight credit cards he received. The episode ends as he looks at the high balance due in shock.
Experiments who appeared or were mentioned in this episode:
- Gigi (X-007): This episode's Monster of the Week; A white Shih-Tzu-like experiment who is designed to annoy people with her constant barking, but otherwise behaves like a typical "good dog". Mertle adopted her before this episode began. Lilo nicknames the experiment "Yapper", hence the episode's title.
- Reuben (X-625): Mocks Gantu for going after a "useless" experiment. When Gantu complains about having to go out in a thunderstorm saying that Hämsterviel doesn't need this experiment, 625 then immediately contacts Hämsterviel to tell him about what Gantu said, which gets Gantu to go out in the rain anyway. 625 stays in the ship as Gantu goes after the experiment.
Tropes featured in this episode include:
- An Aesop: Everyone deserves friends, but in order to make a friend, you have to be a friend.
- Alien Animals: Gigi looks like a Shih Tzu, but is actually an experiment created by Jumba.
- Blatant Lies: When the woman at the dog show registration table (who's also the main judge) asks Lilo what breed of dog Stitch is, Lilo comes up with a ridiculous lie that he's the last of a breed that never even existed called a "blue-furred ectoplasmic detection dog". And the woman buys it!
- Body Wipe: At the beginning while Lilo is reading off her grocery list, an out of focus Mrs. Hasagawa passes in front of the viewer and it cuts to a close-up of Lilo as she's reading.
- Cheaters Never Prosper: Subverted. Mertle cheats and gets away with it. However, she relinquishes the trophy to Lilo for saving her "dog".
- Chekhov's Gun: Done twice with Stitch and his love of coffee. The episode begins with Stitch eating Kona coffee beans and going crazy from the caffeine. Mertle comes by and Lilo tells her about how Stitch goes nuts after he eats coffee. At the dog show, Mertle cheats by getting coffee and tricking Lilo into squirting some into Stitch's mouth, causing him to go berserk and lose the dog show. Later on, when Stitch gets pinned under debris in his fight with Gantu, Lilo intentionally squirts more of the coffee into him to give him the energy boost needed to break free.
- Credit Card Plot: Part of this episode's plot involves Pleakley using twenty-eight credit cards to make purchases. Becomes a Brick Joke when he has to pay for everything he bought with the cards.Pleakley: Oh my goodness! Is that a "balance due" or an intergalactic ZIP code?!note How could they do this to me?! I'm not even a citizen!
- The Dog Is an Alien: The episode's plot twist comes from the fact that Mertle's dog is actually an experiment. That said, there's nothing about her that indicates that she's an experiment. The only hint is her eyes, which are as black as most other experiments, and that's not really enough of an indicator as many dogs in real life have dark eyes.
- Foreshadowing: Stitch, who can be able to tell who is and is not a "cousin", does has some suspicions about Gigi before he and Lilo find out about her true alien nature. Also, Kato Stewart, the champion Surfer Dude judge at the dog show, complains about Gigi's looks, even questioning if she's bred like that on purpose or is she some kind of mutant.
- Getting Eaten Is Harmless: Stitch ingests Gigi during his coffee high at the beginning, forcing Lilo to take her out of his stomach. Her fur is soaked from the brief moment inside him, but she is otherwise unharmed. It's a good thing that she's a experiment, 'cause who knows how acidic her cousin's stomach acids are.
- Good Colors, Evil Colors: Downplayed. Stitch's water bottle is blue, while the coffee-filled bottle Mertle sneaks in is red. Also subverted later on in that Lilo deliberately squirts coffee from the red bottle into Stitch's mouth to revitalize him.
- Never Trust a Title: The title of the episode was meant to mislead viewers of the time using TV Guide or their local listings into trying to figure out who the experiment is, combined with the fact that Gantu spends the episode looking everywhere for the experiment. 007 does get called "Yapper" by Lilo at the end, but since Mertle adopted the experiment well before that, the experiment's name is officially "Gigi". Leroy & Stitch reaffirms this in its credits.
- Nobody Calls Me "Chicken"!: When Mertle says that she and Gigi are not entering all three competitions:Lilo: Shoulda known you'd be scared!
Mertle: Scared?! Ha! Mertle Edmonds never turns down a challenge and neither does Gigi! (Gigi barks, Mertle turns to the registration woman) Enter us in all the competitions, too! (turns back to Lilo) Tomorrow's judgment day, and you and your freakish mutt are going down!
- Oh, Crap!: Lilo has one of these moments when she realizes she overslept on the day of the dog show and finds that Stitch is out of the room, worrying that he left to destroy Honolulu. Subverted, however, when Stitch returns carrying a bucket of ice filled from a hotel ice machine.
- Pet Contest Episode: The episode has Lilo entering Stitch in a dog show against Mertle and her new dog Gigi.
- Resist the Beast: A somewhat downplayed example where one of the main concerns in this episode is Stitch having his destructive programming triggered in the large city of Honolulu. He does succeed in suppressing it... until Mertle changes his water bottle with a bottle filled with coffee.
- Wham Line: "My experiment!" exclaimed by Jumba upon seeing Gigi, who is Experiment 007.
- What Happened to the Mouse?: The dog show includes a retrieving competition, but we never see that happen in the episode despite Lilo and Mertle entering in that along with the other two competitions.