"Chicken, Peter, you're just a little chicken. Cheep-cheep-cheep-cheep-cheep-cheep-cheeeeeeeeeeeeeeeeeeeep."
Even more hilariously brought up later with, "You betray me, you no good. You just a chicken - cheep-cheep-cheep-cheep-cheep." He also looks stiff as a board when he does the chicken movements.