Phineas and Ferb become fashion designers, and their designs become the latest trend.

Meanwhile Dr. Doofenshmirtz has created clones of himself in order to wait in line so that he never has to do it himself.
----
!!Tropes
* AllClothUnravels: Ferb's entire outfit accidentally gets unraveled during the "Forever Summer" montage. He's left standing [[SceneryCensor using the spool he was holding to cover himself.]]
* BorrowedCatchphrase:
** When Phineas sees Candace watching the fashion show on TV, he says to her in the manner of Isabella: "What'cha waaaatchin'?"
** Later in that same scene, after hearing Gaston la Mode will be appearing at the Googolplex Mall, Candace calls Stacy and uses Phineas' catchphrase, "Stacy, I know what we're gonna do today!"
* CheekCopy: "Why is it when people copy their butts, it comes out perfect?"
* CloneDegeneration[=/=]FlawedPrototype: Doofenshmirtz's first three attempts to copy himself. The first one looks too light because it needs more toner, the second one is jagged because of a copy jam, and the third one is extremely ugly, with a giant face and long nose (although the butt was apparently copied perfectly, much to Doof's confusion).
* DontExplainTheJoke: When Doofenshmirtz says "I have captured the rare duct-taped platypus! Get it, you know, like 'duck-billed', uh, never mind".
* EverythingSoundsSexierInFrench: Gaston la Mode sweet-talks Candace into modeling his high-collared outfit for him, calling her "my little ''cou de crayon''". As Ferb points out, it's French for "pencil neck".
* {{Fanservice}}: Isabella looks at her reflection in a funhouse mirror that makes her look like an adult supermodel. She giggles at this.
* FantasyTwist: When Candace's fantasy about being a fashion model turns into a plug for breakfast cereal, she makes a note to stop fantasizing on an empty stomach.
* FashionShow: To show off Phineas' and Ferb's designs.
* FlashInThePanFad: When Doofenshmirtz's clones are seen throughout the mall and everyone decides to imitate their outfit, Gaston tells the boys "your outfits are so [[LeaningOnTheFourthWall three minutes and thirty-seven seconds ago]]".
* GermansLoveDavidHasselhoff: In-Universe: The episode contains two jokes related to France's obsession with Creator/JerryLewis:
-->'''Assistant:''' Pardon, monsieur, I have great news!\\
'''Gaston la Mode:''' A Jerry Lewis marathon on TV tonight?\\
'''Assistant:''' I wish.
* IAmNotWeasel:
** This episode marks the first instance where characters mistake Doofenshmirtz for a pharmacist.
** The ugly Doofenshmirtz clone refers to Perry as a "bunny-rabbit".
* ImOkay: Candace says this after she falls off the runway.
* ImagineSpot: Candace has one as she checks out the catwalk and dreams of being a supermodel.
* ImpracticallyFancyOutfit: Gaston's dresses, whose collars completely cover the models' heads. Only Candace could pull them off due to her long neck.
* MesACrowd: Doofenshmirtz makes clones of himself to infiltrate the mall.
* MundaneMadeAwesome: The "Summer All The Time" collection is really larger-sized versions of the boys’ everyday wardrobe, but it becomes a hit within just a few hours.
* NeverMyFault: Doofenshmirtz blames Perry when [[SelfDisposingVillain he accidentally deletes all of his clones]], even though Perry was tied up and didn't do anything. To be fair, he is used to saying "[[CharacterCatchphrase Curse you, Perry the Platypus!]]" all the time.
* OhCrapSmile: Candace gives one after inadvertently showing her mom the patrons wearing Doofenshmirtz's clothes.
* RewatchBonus: You can see sections of Doofenshmirtz’s mural a few scenes before.
* SceneryCensor: When Ferb ends up naked during the "Forever Summer" montage, the giant spool is covering his crotch.
* ScrewThisImOuttaHere: Candace refuses to wear Phineas and Ferb's clothing line and storms away across the catwalk.
* SendInTheClones: [[MundaneUtility To wait in line for you]].
* SpecialGuest: Creator/FrenchStewart (''Series/ThirdRockFromTheSun'') voices Gaston Le Mode.
* VideoCallFail: Perry arrives in his lair when Monogram is testing the video-call system, and not wearing pants.