Phineas and Ferb help their grandfather relive his glory days as a daredevil.

Meanwhile, Dr. Doofensmirtz tries to get revenge on a childhood bully.
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!!Tropes
* CoolBike: Grandpa Reg's Holy Mackerel
* EmpathicEnvironment: It turns out that all of The Flying Fishmonger's attempts to jump McGregor's Gorge were rained out because his theme song was too dreary.
* StylisticSuck: The Flying Fishmonger's theme song.