S1, E3: When Shirley's father, who is in his late sixties, pulls up in a hot red sports car, the Partridge kids are elated with their jet-set Granddaddy and even ask him to join their group. When he takes them seriously and has his mandolin electrified and learns all the Partridge songs, much to his shock of Grandma, he's ready to tour with his musical kin. In a last ditch effort to discourage the old man's new fling, they convince Reuben to give his unbiased assessment of Grandpa's act. To the shock of the family, Reuben sees a future in the family act for the elder member. He feels that the audience might like the "campy" crooner and might laugh at his novel act. Grandpa, whose voice is at best, average, expected the audience to take him seriously and to "dig" him for what he is. Meanwhile, Grandma is vexed over Grandpa's new image. She tells Shirley how he's wearing sideburns, taking skydiving lessons, talking about running around with the chorus girls and -- because he wanted her to "catch up," he bought a mini skirt for Grandma! Determined to have his debut, Granddaddy gets Reuben to book him on the same bill with his grandchildren. Just as he is about to sing his opening rock number, Grandma stands up in the audience and, with all eyes on her, requests that Grandpa play the song they courted to, "Bye Bye Blackbird." At first embarrassed, Grandpa is later inspired by the audience who appreciate Grandpa for the sincerity of the old song, instead of the hilarity of him singing rock and roll. He promises Grandma a trip around the world if she promises to keep up with him.