Crack That Whip
The boys build a roller-derby rink for their grandma, who once was on a championship derby team, so she can skate against her onetime rival. Meanwhile, Doofenshmirtz believes a statue of a bearded man is mocking him because he can't grow facial hair, leading him to create a machine to solve his problem for him.
Not on the schedule right now. See Phineas and Ferb