The shortened form of the word pectoralis major. Guys who take good care of there body and keep a physically active life style tend to get these. They are located in the area where women have there tits. Namely the chest. Girls like a good looking guy with nice pecks. They are usually very muscular. They look nice too. Wish i had nice pecks.
My friend Nick always goes to P.E with out his shirt. The girls like looking at his pecks. The teachers do too.