Phineas and Ferb are excited to go to the circus, but when they discover it's been cancelled, they decide to mount their own circus with their friends.
Meanwhile, Jeremy gives Candace wild parsnips -- which she is allergic to, the result being that her voice is significantly deepened. This might prove a problem for Dr. Doofenshmirtz, who has invented a device with the aim of making everyone else's voices become ''higher'' so his will sound lower by comparison...can Perry the Platypus stop his plot ''and'' make his cue in the show?
* AffectionateParody: As suggested by the title, the kids' circus is a good-natured spoof of Creator/CirqueDuSoleil productions.
* BigNo: Candace lets one out when she succumbs to her parsnip allergy.
* CrossDressingVoices: Allergic Candace is voiced by Dan Povenmire, one of the show's creators & the voice of [[MadScientist Dr.]] [[HarmlessVillain Doofenshmirtz]].