Zippy, a Nanday Conure, is Bill's favorite parrot. In "His Visit: Day One", Shaun finds Zippy lying on its back in its cage, apparently dead. After Bill takes Zippy out of the cage, Shaun touches the bird and it comes back to life in Bill's hands. Upon witnessing this, Bill exclaims "Jesus, Mary, and Joseph!"
Bill denies that Zippy was dead, and claims that Shaun will understand when he's older.
In "His Visit: Day Two", Bill smuggles Zippy into Shaun's hospital room in his jacket pocket. Recalling actions and words from the previous day, Bill has the bird "kiss" Shaun on the cheek. This brings Shaun back to life from his brain dead state ("much improved", as Bill says).
In "His Visit: Day Two Continued", Zippy shits in Bill's pocket... twice!
In "His Visit: Day Three", Bill talks to Zippy while Zippy "conveys" his thoughts to Bill. Zippy suggests that Bill become friends with Freddy, a notion that Bill finds "senseless and offensive". Still, Bill brings coffee and donuts to Freddy, saying, "I'm here on orders from my bird.