Sweater Chicken is a reappearing boss in Chicken Invaders: Revenge of the Yolk.
It is the third, eight and eleventh boss in the game. The only difference is that every other encounter gives you more clothes to take from it (health).
It attacks with shooting omnidirectional eggs. As you fight it, it's clothes come off. When you take enough clothes off it, the chicken will be beaten.
For a list of all Bosses & Enemies go here.