The very last episode of Forever Summer.
Phineas and Isabella wake up one day and they do what they always do. When Ferb comes over, they start building a museum. "I need my repair box!" said Phineas. Dr. Poofenplotz arrives suddenly, she swoops down and kidnaps Ferb and Isabella. Phineas watches them fly away, along with the floating baby, who makes a farting noise. Phineas runs off into another show called Kid vs. Kat and partners up with Coop and Dennis. Phineas brings them over to his world and powers up coop and Dennis. When Phineas enters Dr. Poofenplotz's cave, Coop and Dennis get captured. Now it 's up to Phineas to save them. Phineas finds his friends locked up in a cage, he finds Isabella saying "I'll cry if i want to". Phineas sprouts claws and cuts the cage open and frees them!. On their way out they find Candace in a cage and see that Jermey is with her and he frees them. When they get home they start working on their upcoming TV series, Lauren is Explorin.
Phineas had the ability to grow claws just like the superhero.
Isabella says" I'll cry if i want to" part of the lyrics to the song Potty Training Flowgo, which is also a parody of the song It's My Party.
The Bebe Lilly song Hello Papi plays in the background at the end credits.