A cute stinkbomb of an experiment helps Lilo to be accepted by the hula girls, causing Stitch to become jealous of all the attention the experiment gets. When he lets Gantu have the experiment, however, he soon becomes guilty for his actions and goes out to take Mr. Stenchy back.
Lilo and Stitch have just rescued a cute pink experiment from Gantu. As Lilo and Stitch refill the X-Buggy at a gas station, Mertle and her posse pass by. Elena wonders if they should invite Lilo to their FHGH (Future Hawaiian Girls of Hawaii) tea party. Seeing the cute experiment for themselves, they decide to do so, provided that Lilo brings the creature with her. Lilo sees this as a chance for Mertle's gang to finally like her and accepts the invitation.
Back at the Pelekai residence, Jumba says that Experiment 254 was indeed made to be very cute. However, this is so that Jumba's enemies would be tricked into taking the experiment in, as 254 is designed to release a very horrid smell that will clear a large area for decades. Lilo, naming 254 "Mr. Stenchy", wants to keep him, but Jumba says that they can't because the odor is that bad, so he needs to be flown out of Earth very soon — 254's odor is set to release 42 hours within his activation. When Lilo says how Mr. Stenchy allowed her to be invited to Mertle's tea party, Jumba does let the little girl keep 254 for the time being, but he will be making a rocket to send the experiment away.
Stitch expresses much displeasure towards Mr. Stenchy and would rather get rid of him as soon as possible. Everything seems to be going smoothly with Lilo and Mr. Stenchy at the tea party until Stitch crashes it and eats all the food. An angry Mertle tells Lilo that she has one more chance at the next tea party to stay in the FHGH, but only if she brings Mr. Stenchy and leaves Stitch back home.
Later that evening, the Pelekai ʻohana except for Stitch and Mr. Stenchy leave to go shopping, with Lilo telling Stitch to look after Mr. Stenchy. Once she leaves, the pink experiment tries to get along with Stitch, but the blue experiment decides to stuff him in the pantry instead. Gantu then arrives at the house to take 254 and attacks Stitch, who easily takes him down. However, Stitch then gets an idea to be rid of Mr. Stenchy, so he then lets Gantu get up and chase him to the pantry, where the big whale-like alien finds 254 and captures him. After the ʻohana returns to find the house in a mess, Stitch expresses that Gantu took Mr. Stenchy (leaving out the fact that he let Gantu take the experiment). However, he starts to feel guilty when Jumba mentions that Gantu is most likely sending 254 to Hämsterviel as they speak.
The big alien is beginning to do just that back at his ship, with Reuben hoping that he finishes the teleportation up soon, but then he falls for the cute little experiment's charms. He decides to keep Mr. Stenchy for himself, saying that Hämsterviel can wait.
The next day, Lilo tells Nani how upset she is over losing Mr. Stenchy, saying that she won't be invited back to Mertle's tea party without him. Nani retorts that Mertle and the other girls wouldn't make good friends, especially when compared to Stitch. This brings more guilt down on the blue alien, so he disguises himself as Mr. Stenchy to try to help Lilo stay in FHGH. It doesn't work; at the tea party, he and Mertle get into a fight that causes damage to her house, prompting her to kick out and ban Lilo from the group.
At night, Lilo apologizes for Stitch for giving Mr. Stenchy too much attention. She still falsely believes that Stitch tried to protect Mr. Stenchy from Gantu, and says to him that she appreciates how loyal he is to her. After she falls asleep, Stitch becomes so guilty that he decides to go rescue Mr. Stenchy from Gantu, bringing up an image of Gantu's ship on his and Lilo's computer beforehand.
Gantu is still doting over Mr. Stenchy, much to Reuben's annoyance, when Stitch invades the ship. Gantu quickly captures Stitch in a containment capsule and starts preparing to send the blue alien to a desert asteroid, but Mr. Stenchy distracts him. Reuben is so envious of Mr. Stenchy that he decides to work with Stitch to have the latter take the pink experiment back. Around the same time, Lilo wakes up from the bright light of the computer monitor and figures out that Stitch has gone to Gantu's ship to rescue Mr. Stenchy.
Just as Gantu finally starts to begin the teleportation process, he sees Reuben in the teleportation tube. Stitch then attacks Gantu and tries to take Mr. Stenchy, but Gantu blasts him into a net. Thankfully, Lilo, Jumba, and Pleakley arrive and Jumba stops Gantu. Lilo frees Stitch from the net, but when she tries to get Mr. Stenchy to walk back to her, the experiment notices Stitch next to her and runs back to Gantu. He tells Lilo about Stitch locking Mr. Stenchy in the pantry, to which Stitch admits that it's true. Realizing about his jealousy, Lilo forgives Stitch for his actions, and he forgives her for not paying enough attention to him.
By that time however, Mr. Stenchy finally unleashes his odor. The powerful stench offends everyone else except for Pleakley, who finds it to be delightful. He says that the experiment's scent is considered a rare and valuable perfume on his home planet of Plorgonar. Gantu still wants to take Mr. Stenchy back, but the experiment's odor is too unbearable for him, so he gives 254 up to Lilo and Stitch.
Jumba puts Mr. Stenchy on a small rocket hooked to the back of the X-Buggy and sends the experiment off into space, where he ends up at his "one true place" on Plorgonar and is happily taken in by a Plorgonarian couple.
Experiments who appeared or were mentioned in this episode:
- Mr. Stenchy (X-254): This episode's Monster of the Week; a ridiculously cute pink experiment who is designed to lure enemies with his cuteness to take him in, then release a noxious odor forty-two hours after activation. The odor is so horrid that it can render a forty square mile area uninhabitable for decades.
- Reuben (X-625): Surprisingly, even he is jealous of Mr. Stenchy, making this episode the only time where Reuben expresses jealously towards anyone.
Tropes featured in this episode include:
- An Aesop: A true friend is someone who stays by your side and accepts you for who you are, not for something that you have. Also, it stinks to be jealous, but it's better to come clean with those feelings than let it fester.
- Arson, Murder, and Jaywalking: Gantu causes damage inside Lilo's house, takes away Mr. Stenchy, and steals all the cans of ravioli from the pantry.
- The Atoner: Once he becomes incredibly guilty over letting Gantu take Mr. Stenchy, Stitch first tries to help Lilo stay in Mertle's FHGH group, then later goes out to rescue Mr. Stenchy from Gantu.
- Call-Back: After capturing Stitch, Gantu prepares to send him off to a desert asteroid, just like when he tried to transport 626 (the pre-reformed Stitch) to one back then, only this time Stitch would have been teleported instantaneously.
- Cuteness Proximity: Mr. Stenchy was designed to invoke this trope, so unsuspecting enemies could take him in. The only creatures that are immune to his cuteness are other experiments.
- The Dreaded Pretend Tea-Party: Subverted; Lilo finds being invited to one of Mertle's tea parties as a sign that she's finally accepting her.
- Easily Forgiven: When Stitch is forced to admit that he locked Mr. Stenchy in the pantry and let Gantu take the experiment, Lilo—understanding why Stitch did so—agrees to forgive him for his actions if he forgives her for neglecting him, to which he does so.
- Enemy Mine: Reuben doesn't like Mr. Stenchy either, so he and Stitch set up a plan to have the latter take back Mr. Stenchy from Gantu.
- Evil Smells Bad: Mr. Stenchy's odor can make a large area uninhabitable for decades.
- Fun with Acronyms: FHGH stands for the Future Hawaiian Girls of Hawaii.
- Good Angel, Bad Angel: Spoofed with Stitch having two bad devils when he wonders if he should let Gantu take away Mr. Stenchy.
- Green-Eyed Monster: Other experiments are immune to Mr. Stenchy's charms, so Stitch and Reuben express much jealousy when their partners dote over the cute experiment.
- Inflating Body Gag: At the gas station, Stitch inflates himself like a balloon when he sucks air from one of the X-Buggy's tires, causing him to float until he belches.
- Innocent Blue Eyes: Sweet little Mr. Stenchy has a couple of big ones. Subverted in that they help him trick enemies into taking him in so he can release his awful odor.
- Meadow Run: Played for Laughs when Gantu has a sepia-toned Imagine Spot of him in a meadow running towards Mr. Stenchy and cuddling him.
- Mundane Utility: Reuben is seen with his claws extended for the first time... only to use them to spread some grape jelly on his sandwiches.
- Mythology Gag: When Lilo says that she'll keep Mr. Stenchy no matter how bad his odor will produce, Stitch becomes so angry that he screams into a pillow, much like how Lilo and Nani did after their fight in the original film.
- Non-Standard Character Design: Mr. Stenchy's eyes have visible sclerae, irises, and pupils, unlike most other experiments who have eyes that appear to be black or of a single color.
- Oblivious Guilt Slinging: After Stitch deliberately lets Mr. Stenchy be captured, Lilo laments on how losing the experiment means that she'll be unable to bring him to a tea party held by Mertle's snobbish posse to be accepted as their friend. Nani points out that these girls probably wouldn't make good friends anyway; Stitch, on the other hand, is someone Lilo can depend on. Every affirmation made of how Stitch would never do anything to hurt Lilo sends him sinking further and further into his chair. He tries to atone for it by dressing up as Mr. Stenchy for the girls' tea party, though it doesn't exactly work out. At bedtime, he becomes even guiltier when Lilo says how loyal of a friend he is to her and believes that Stitch tried very hard to protect Mr. Stenchy.
- Paper-Thin Disguise: Stitch disguises himself as Mr. Stenchy with a pink onesie and a pink bucket with Mr. Stenchy's face poorly painted on it to try to help Lilo stay in the FHGH group. However, he is unable to suppress his Big Eater habits and mischievous nature, and the disguise rips apart after Mertle realizes who he is.
- Ridiculously Cute Critter: Mr. Stenchy was made to be one, and by God is he so freakin' cute!
- Weaponized Stench: Mr. Stenchy can release a powerful odor upon unsuspecting victims who are caught off guard by his cuteness.
- With Friends Like These...: Nani's talk with Lilo before the second tea party attempt, showing her that Mertle's gang aren't the kind of people to be friends with, unlike Stitch who always stays true to her.Nani: Lilo, if they only liked you because you had a cute pet, then who needs 'em? You gotta know who your real friends are.
Lilo: Like who?
Nani: Hmm? Like Stitch, for one. He's a royal pain, but he's loyal, and he'd never, ever, ever do anything that would hurt you. That's a true friend.
Lilo: I know. Stitch is the best. I wouldn't trade him for anything or anybody. - Visible Odor: Once Mr. Stenchy releases his smell.
- You Are Grounded!: Mertle accidentally breaks a window when she throws a crumpet at Stitch, leading her to panic that she'll be grounded for a month. Exaggerated when the following shenanigans lead to her breaking the entire back porch by accident. Appropriately, she wonders:Mertle: Can you get grounded for infinity?
- Your Size May Vary: When Gantu first attacks Stitch at the Pelekai residence, he's two stories high, but then when he chases after Stitch inside the house, he can inexplicably fit inside (although he's still just too big for the front door).
