Preppy shirt is a term used to describe a type of shirt that is typically associated with the preppy style. The most common type of preppy shirt is the POLO, which is a short-sleeved shirt with a collar and two or three buttons at the neckline. It is usually made of cotton or a cotton blend and is often seen in solid colors or with stripes. The POLO shirt is a classic preppy look that has been popular for decades.