Katherine and the Big One

The fiftieth and final episode of Season 37. Katherine has just about had it with Doofenshmirtz, and Doofenshmirtz has had enough of Katherine. Doof creates the ultimate monster to annihilate her. Katherine gathers some friends to help stop the creature. Includes a silly song break, but a short takes the place of it.

Episode Summary
Katherine is busy minding her own business. She's throwing darts at a picture of Doofenshmirtz. She's just about had it with him. Meanwhile, at Doofenshmirtz Evil Incorporated, Doof is throwing darts at a picture of Katherine. He's about had it with her, and it was because of a silly ice cream truck. He calls for Norm and they need to get building, he knows what he's gonna do today. With the boys, they have Maddie and Haven over. They're deciding what to build. Phineas has an idea of training sharks to dirtbike, and Ferb suggests a love magnet for Phineas and Amanda. Phineas rolls his eyes and grunts. Maddie suggests making high-tech swords for combat. Phineas thinks that sounds awesome and decides to do it. With Doof, the monster, which he calls "The Big One", is finally ready. He tells the Big One to go out and destroy Katherine. Norm applauds Doof, and Doof takes a bow. Vanessa still thinks her dad is tinkering with toys. Doof facepalms. With Katherine, she's busy walking in town when she spots the Big One. She wonders what it wants. Then, it starts heading for her. Then it cuts to the short. After the short, it finally reveals what happens to Katherine. She tries uppercutting the beast. It leads to a chase around town. Phineas and Ferb hear the chaos. Katherine comes running into the backyard. She needs as much help as she can to destroy a monster. Phineas is glad they made extra swords. So they gather Isabella, Buford, Baljeet, Irving, Django, Bailey, Hannah, Jenna, Lauren, Tanner, Kendall, Haven, Mallory, Heidi, Ford, Caleb, Cassie, Katie, Wesley, and Maddie. Maddie thinks Olivia would love doing something like this. They all go attack the monster with their swords. It's no use. Then, Buford discovers a puree feature on the swords. He threatens the beast with it. The Big One starts to flee. Doof is watching the action from a camera, and is trying to tell the Big One to turn back and fight. Norm says this scheme is much worse then pamphlets with convincing fonts. The Big One eventually heads for the mountains. It eventually ends up at the gold mine, which both Bailey and Kendall remember. They start slashing at the monster. Again, it's no use. Doof starts cheering. Then, Katherine presses a death by monkeys button. A whole bunch of monkeys come and attack the monster, ripping at its metal flesh and computer chips. Doof is wondering why his camera connection is so fuzzy. He hopes it's not another kiddy TV show. Then, he realizes Katherine had defeated the Big One, but it left a lot of destruction in town. Phineas says not to worry, him and Ferb got it covered. Everyone cheers because they helped a friend. Katherine feels really proud, she probably will never have to deal with Doofenshmirtz again. Doof is furious. He says Katherine may think it's over, but he'll be back, some other day.

Songs

 * Bust Your Brothers (instrumental)
 * The Big One!

The "Too Young" Line

 * Maddie: "Gee, Olivia would probably like action like this!"
 * Baljeet: "Yes, yes she would!"

Ferb's Line
"We did it!"

Whatcha Doin
Haven and Maddie at the same time

Perry's entrance to lair
None seen

Evil Jingle
Doofenshmirtz Evil Incorporated, (fast) where Doofenshmirtz and Norm are building an overcomplicated monster to totally destroy a girl which they have been seeking revenge on since a silly little predicament with an ice cream truck!

Continuity

 * Ninth time Doofenshmirtz does something against Katherine ("Katherine v.s. Doofenshmirtz", "Believe In Myself", "Amanda's Inside Story", "The Chronicles of Irving", "Katherine's Last Stand", "Bailey Strikes Gold", "Undercover Katherine", "Doofenshmirtz Goes Country")
 * Bailey and Kendall remember the gold mine ("Bailey Strikes Gold", "Kendall's Mission")
 * The ice cream truck is brought up by Doofenshmirtz and the jingle singers ("The Ice Cream Truck")
 * Doofenshmirtz mentions kiddy TV shows ("Hide and Seek")
 * Norm mentions pamphlets with convincing fonts ("Ferb Latin")
 * An instrumental of Bust Your Brothers is heard ("Phineas and Ferb-Busters!")
 * Katherine has a picture of Doofenshmirtz driving a truck ("Road Trip")
 * Doofenshmirtz has a picture of Katherine hosting the sing-along ("The Phineas and Ferb Sing-Along Episode 3")
 * In the credits, Kenzi comes back from Korea ("Kenzi Goes to South Korea")
 * Vanessa mentions Doofenshmirtz playing with toys ("This Is Your Backstory")

Allusions

 * VeggieTales: The Going Up short is used, taking place of the silly song
 * Toy Story 3: The death by monkeys button is the same one used in the movie
 * Rugrats: The Big One bears a resemblance to Reptar