Prep

Noun (Prep): Comes from identifiying one who goes to a prepratory or "prep" school (typically on the East Coast), or a school with the intent of preparing its students for college (often Ivy League). 

Has come to be an label for those who conform to typical teenage behavior, in areas like clothing, school behavior, and sports participation, because preps usually are more ambitious and/or image-conscious than others. 

Popular belief is that preps hate nerds/goths/punks/etc, however, generally, preps pay little attention to other "types," and those who hate preps with the most passion are those who were once preps and have recently gone away from their previous behavior, and often people who are posers intent on protecting their alternative-ness. 

Prep has become to be nearly synonymous with conformist, to the point where most preps have been in denial of their typecast, and it is seen as an insult in the eyes of many. 

Preppy is the adjective form, Preppily is the adverb.

The prep dreamed of going to a school that wasn't too far from where her quarterback boyfriend got a scholarship. 

Bob wouldn't talk to Annie; He thought her interest in MTV and popular culture made her too preppy. 

Tiffany started dressing very preppily over the summer, shedding her all-black dress code for the latest styles.

Typically, this word has become a derogatory name for a guy or a girl who takes pride in the way they approach, and appear, in life. Common misconceptions about "preps" are that we are a bunch of cocky, New England elitist types who have more money than God, himself, and an inherent desire to flaunt it in the form of clothing, cars, housing, education and social standing. 

First off: You don't have to be from the north to be a prep. Let me make this very clear. What prep initially implies is that you went to preparatory school, hence the word "prep" (I'll discuss later how it's a cultural identity). There are plenty of good southern preparatory schools, which include Woodberry Forest, Virginia Episcopal School...you get the idea. There are good preparatory schools in every corner of this country, but it's the New England boarding schools that have assisted in establishing this stereotyped location. 

Let's get on with true prep culture: 

A prep's wardrobe consists of some expensive clothing, but they've had it for the better part of a decade--excluding the two Vineyard Vines polos they got for their birthday and the 50% off sale at Brooks Brothers--indicating the true preppy trait of valuing "classic" over "trendy". We don't buy into the Lacoste trend of now, but we will gladly wear "handed down from dad" Lacoste polo shirt when it still maintained an association with Izod, which was well before it became the token icon of a sold out, soulless and materialist...

in Urban Dictionary