Rollercoaster

Season 1, Episode 1, Part 1 - "Rollercoaster"
(Episode #6, Part 1 on iTunes, first aired on 8/17/2007)

Episode Summary
In the series premiere (meaning it contains quite a bit of random character exposition), while Mom goes to the store to "pick up a few things", Phineas and Ferb decide to build a rollercoaster in their backyard. Meanwhile, Agent P is sent to check on Dr. Doofernshmirtz, who has bought up 80% of the country's tinfoil. While Phineas and Ferb get the proper permits for their coaster, Dr. Doofernshmirtz reveals that he has covered the eastern seaboard of the U.S. with tinfoil. Using a "magentism magnifier", the Dr. will pull the east coast toward the west, reversing the rotation of the Earth. While Phineas, Ferb and several of their friends ride the roller coaster, the magnetism magnifier instead pulls all of the tinfoil off of the buildings on the eastern seaboard and sends a huge ball of tinfoil hurtling back at Agent P and the Doctor. Agent P fires a rope at a helicopter, and manages to escape before the tin foil ball destroys the top part of the Doctor's building. He takes the magnet with him beneath the helicopter, and the magnet ends up picking up the roller coaster, removing all evidence of Phineas and Ferb's backyard project.

The "too young" Line
Factory Manager: Aren't you a little young to be a roller coaster engineer? Phineas: Yes, yes I am. Factory Manager: Well, I must say I'm very impressed. The forms all seem to be in order, although I've never seen them filled out in crayon before. So, if there's anything I can get you, anything at all.. let me know.

Phineas' Philosophical Line
"So, what should we do tomorrow? There's a world of possibilities.  Maybe we should make a list!"

Ferb's Philosophical Line
(In reference to the platypus) "They're the only mammals to lay eggs."