Platypus Day

Phineas and Ferb make a holiday to celebrate Perry, but this causes Perry to not be able to fight Doofenshmirtz for the day, so Major Monogram has to hire the new agent, Steve the Chameleon to fight him instead. Meanwhile, Doofenshmirtz finishes off his Enlarge-Inator.

Episode Summary
It opens up to Phineas, Ferb and Perry in the backyard. Phineas tells Ferb that Perry has to be the best pet ever, and wonders what it would be like if everyone knew how great Perry was. Phineas then decides that they should make Perry a holiday! Perry then disappears, but Candace sees Phineas and Ferb plotting and runs out to bust them, tripping over Agent P. Agent P goes back to mindless pet mode and Candace carries him to the boys and flops him down angrily. Phineas says "Oh there you are, Perry" and pulls him over to the plans.

In Perry's lair, Monogram asks Carl where Perry is. Carl replies that he's not sure, so Monogram contacts him on his wristwatch. Perry doesn't answer, worrying Monogram. Monogram tells Carl to send for the new agent.

In Phineas and Ferb's room, Steve is in a small glass habitat wearing a wristwatch. Carl appears on it and asks for Agent S. Steve puts on a fedora and stands up, looking at the watch. Carl informs him that Agent P hasn't answered his wristwatch and they need Steve to go get Doofenshmirtz. Steve salutes Carl and leaves.

Meanwhile, Phineas and Ferb have finished planning and have made a huge Perry-shaped stage. On top of it is a pedestal which has Perry on it. A crowd gathers and Phineas and Ferb introduce Platypus Day. Pedro and Arthur are hosting the Platy-Games, Isabella has the Platy-Cake and Perrookies, Buford and Baljeet are hosting the Perris Wheel and Irving is selling souveniers. They all sing Platypus Day and it goes to DEI.

At DEI Doofenshmirtz asks himself where Perry is and Steve breaks through. Doofenshmirtz is confused by Steve's appearance and Steve shows him Monogram on the wristwatch, who explains. Doofenshmirtz traps Steve in a snowglobe similar to the unused one from Journey to the Center of Candace. He then introduces his Enlarge-Inator, which he says he's been working on for awhile. He pats it, causing it to fire. He remarks that it's touchy.

At the Platypus Day Party, several kids are riding the Perris Wheel when the Enlarge-Inator hits it. The Perris Wheel grows huge, causing Buford to demand double the original price.

Doofenshmirtz reveals his plan to enlarge the ocean in order to flood the Tri-State Area. When all of the people are panicking, he'll come out with the Shrink-Inator and save the day and will be given control of the Tri-State Area. He pats it again and it fires at the snowglobe, hitting Steve. Steve enlargens to his size during The Lizard Whisperer and in enlargening breaks the Enlarge-Inator and DEI. He also hits the Shrink-Inator, which fires and shrinks all of the Platy-Games to normal size just as Candace comes outside with Linda. The Shrink-Inator then hits Steve, who shrinks back to normal size and rips the wires apart, firing it again at Doofenshmirtz. Steve then escapes as Doofenshmirtz yells "Curse you Steve the Chameleon!"

At the Flynn-Fletcher backyard, Linda asks the boys what they did all day. Phineas replies that they made Perry a holiday. Linda says that it's cute and drags Candace back inside as Steve walks up. Ferb says "Oh, there you are, Steve" and Phineas suggests that they make "Chameleon Day" tomorrow.

Songs

 * Platypus Day
 * Steve the Chameleon Theme

End Credits
Steve the Chameleon Theme.

"Too Young" Line
None.

Ferb's Line
"Ferb: Oh, there you are, Steve.

Phineas: Maybe tomorrow we can make "Chameleon Day"!"

- Phineas and Ferb.

Whatcha Doin'?
None.

Hey, Where's Perry?
"Monogram: Hey Carl, where's Agent P?"

- Monogram.

"Doofenshmirtz: Hm, where's Perry the Platypus? He should be here by now."

- Doofenshmirtz.

Perry's Entrance to his Lair
None.

Evil Jingle
Doofenshmirtz Evil Incorporated!

Memorable Quotes
"Buford: Get a ride on the Perris Wheel, 10 dollars!

(Enlarge-Inator beam hits it)

Buford: ...Get a ride on the Perris Wheel, 20 dollars!"

- Buford

Background Information

 * Several previous episodes are referenced in this episode:
 * Steve returns, along with the Enlarginator, allthough the Enlarginator was the Gigantinator in The Lizard Whisperer.
 * When Doofenshmirtz pats the Enlarginator and it fires, this is a reference to Misperceived Monotreme, where the Least-Likely-Inator does the same thing.
 * When the Enlarginator hits the Perris Wheel, Buford acts similarly to the cucumber saleswoman from Meatloaf Surprise.
 * Fourth time a different agent is hired to fight Doofenshmirtz for Perry. Sergei in Oh, There You Are, Perry and Perry the Actorpus and Pinky in Fireside Girl March.
 * Steve is actually called Agent S like Sergei.
 * This episode reveals that Pedro's last name is Jackson and Arthur's last name is Kampbell, as well as Baljeet's last name being Jai.

Cast

 * Vincent Martella as Phineas
 * Thomas Sangster as Ferb
 * Alyson Stoner as Isabella
 * Ashley Tisdale as Candace
 * Dee Bradley Baker as Perry
 * Bobby Gaylor as Buford
 * Dan Povenmire as Major Monogram
 * Jeff Marsh as Doofenshmirtz
 * Tyler Alexander Mann as Carl