Rollercoaster
In the pilot episode, Phineas and Ferb decide to build this massive backyard attraction to cure their boredom.
A rollercoaster
Phineas and Ferb carve Candace's face onto Mount Rushmore to celebrate this specific July milestone.
Her 15th Birthday
Phineas and Ferb enter the neighborhood soapbox derby, but their mother thinks they are just playing a classic video game when she spots their souped-up vehicle which bears this racer number.
1
This is what Phineas and Ferb build in their backyard on the hottest day of the year.
A beach
In this episode, Phineas, Ferb, and Isabella put on ten-gallon hats at Clem's Carnival to become these traditional American ranch hands.
Cowboys
After being tricked into thinking her brothers were just playing in the backyard, Candace is caught in a rainstorm while trying to bust them at this specific location.
The Tri-State Area
Dr. Doofenshmirtz sets up his secret lair inside the carved stone head of this specific U.S. President on Mount Rushmore.
Abraham Lincoln
While phoning her mom to tune in, Candace is frustrated to find that her friend Isabella's house is equipped with too many of these, causing her to miss her brothers' big race and see a dandruff shampoo commercial instead.
Remotes
Dr. Doofenshmirtz blames his hatred for these garden decorations on the fact that he was forced to dress up as one in his youth.
Lawn gnomes
Dr. Doofenshmirtz puts helmets on these tiny, wood-eating insects so he can launch a new aluminum siding business.
Termites
This girl scout leader and Phineas' best friend is the first to buy a ticket for the boys' rollercoaster.
Isabella
Before doing Mount Rushmore, Phineas notes that this disastrous birthday gift from the previous year "didn't work out so well".
A gorilla in a cake
Dr. Doofenshmirtz brings this inflatable-destroying device to the stadium, threatening to use it to flatten every ball and float in the Tri-State Area.
The Deflate-inator
While Phineas and Ferb are surfing, Agent P investigates Major Monogram's report that these garden items protect homes against this dark force.
The evils of black magic
While trying to stop Doofenshmirtz, Agent P (Perry) ends up dangling over a pit filled with this hot, molten rock.
Lava
Dr. Doofenshmirtz plans to destroy the rollercoaster with this specific type of "inator" ray.
The Magnet-inator
Just as Mom is looking through a coin-operated telescope to see the boys' huge invention, this natural feature erupts to block her view.
The "Ol' Reliable" geyser
While driving the car, Phineas wears this on his head, which Isabella compliments as being "manly."
A racing helmet
In a fun twist for early episodes, this character actually tries to prevent her mom from seeing the boys' big project because she wants to enjoy the beach with Jeremy.
Candace
After herding the stampeding cattle, the boys stop for lunch, and the daily special at the local mall food court serves up this very same meat.
Beef
When the rollercoaster soars through space, this astronaut makes a cameo to point out that they are flying a little too close to his capsule.
Neil Armstrong
When Candace's carved stone face starts crumbling, Phineas, Ferb, and a few friends calmly sit back and roast these.
Hot dogs
When the Phineas and Ferb racing car takes off to take the lead in the race, it briefly features one of these girly accessories on its hood, provided by Fireside Girl Gretchen.
A bow
During the surfing competition, Ferb sings this specific type of song while playing the guitar.
A Jamaican rap
To help calm the frightened animals, Phineas asks Ferb to play this stringed instrument, but a snapped string only makes the cows run faster.
A guitar