The Wikipedia article on the upturned collar is surprisingly informative and relevant.
With origins predating the 20th century, the upturned or 'popped' collar was somewhat ubiquitous. Even President James Buchanan wore upturned collars:
At this time, upturned collars were detachable, and were notorious for being quite uncomfortable and stiff.
The modern iteration of the 'popped collar' is summarized especially well in the aforementioned Wiki article:
"With the advent of the tennis shirt, however, the upturned collar took on a whole new purpose. In 1929 René Lacoste, the French 7-time Grand Slam champion, decided that the stiff dress shirts and ties usually worn by tennis players were too cumbersome and uncomfortable for the tennis court. Instead, he designed a loosely-knit pique cotton shirt with an unstarched, flat protruding collar and a longer shirt-tail in back than in front. This came to be known as the tennis shirt. Lacoste's design called for a thick pique collar that one would wear turned up in order to block the sun from one's neck. Thus, the tennis shirt's upturned collar was originally designed by the inventor of the tennis shirt, himself, for ease and comfort on the tennis court, aiding the player by helping to prevent sunburn."
Since then, the shirts have transcended to popular culture and other sports. Think Diane Keaton in Annie Hall, James Dean in Rebel Without a Cause or Manchester United star Eric Cantona.
Today, popped collars enjoy a mixed legacy and reputation. While many people still use them in the same way René Lacoste intended early in the 20th century, the frat bros and 'wannabes' use them to attain that 'preppy' look.
While it is a so-so reference at best (it's hard to find any sources on this subject that aren't dubious), this site provides an interesting supplement to the Wiki article mentioned above.