S.P.L.A.T.'s Back (2) - S1.E26

Beegle, disguised as Big Bad Bird, pretends to follow the Chicken's orders. The Chicken heads out to sea, along with his birds, while Grape Ape secretly follows them underwater. Eventually, Beegle reveals that the birds were merely controlled by a whistle. As for the Chicken, he turns out to be the birdkeeper in disguise.