Packing peanuts are generally extra roosters added to the order. Because MPC tends to cater to customers who live in an urban setting, they know that roosters are generally not welcome, as us city folk can't have them. Because of this, shipping is generally a bit more for small orders than other hatcheries. If you do get extras in the order, it's generally pullets, not roosters. (Of course, sexing is never 1%, but that's the chance you take!)