Sheep in the Big City (2000)

Sheep can't hold a steady job because the Top Secret Military Organization is always pursuing him. At the top Secret Military Base, Gen. Specific fires all of his staff (except for Private Public and the Angry Scientist) and decides to hire new ones. Sheep without a job applies for it. Gen. Specific doesn't know that it was Sheep, hires him. The Angry Scientist discovers the new recruit is really Sheep and proceeds to tell Gen. Specific. Gen. Specific tells Sheep that he should capture Sheep to prove he isn't really Sheep. Sheep fooled them by bringing a Gorilla in a sheep costume.